344 lines
36 KiB
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344 lines
36 KiB
HTML
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<title>std::ranges::set_union, std::ranges::set_union_result</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span>set_union, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>set_union_result</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-algorithm.html">algorithm</a>‎ | <a href="cpp-algorithm-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-algorithm.html"><algorithm></a></code></div>
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<div>调用签名</div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I1, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I1<span class="sy1">></span> S1,<br /></span>
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<p> std<span class="sy4">::</span><span class="me2">input_iterator</span> I2, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I2<span class="sy1">></span> S2,<br />
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std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O, <span class="kw1">class</span> Comp <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">less</span>,<br />
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<span class="kw1">class</span> Proj1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>, <span class="kw1">class</span> Proj2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">mergeable</span><span class="sy1"><</span>I1, I2, O, Comp, Proj1, Proj2<span class="sy1">></span><br />
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<span class="kw4">constexpr</span> set_union_result<span class="sy1"><</span>I1, I2, O<span class="sy1">></span><br />
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set_union<span class="br0">(</span> I1 first1, S1 last1, I2 first2, S2 last2,<br />
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O result, Comp comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>,<br /></p>
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Proj1 proj1 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj2 proj2 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> ranges<span class="sy4">::</span><span class="me2">input_range</span> R1, ranges<span class="sy4">::</span><span class="me2">input_range</span> R2,<br /></span>
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<p> std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O, <span class="kw1">class</span> Comp <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">less</span>,<br />
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<span class="kw1">class</span> Proj1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>, <span class="kw1">class</span> Proj2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">mergeable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>, ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R2<span class="sy1">></span>,<br />
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O, Comp, Proj1, Proj2<span class="sy1">></span><br />
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<span class="kw4">constexpr</span> set_union_result<span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>,<br />
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ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R2<span class="sy1">></span>, O<span class="sy1">></span><br />
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set_union<span class="br0">(</span> R1<span class="sy3">&&</span> r1, R2<span class="sy3">&&</span> r2, O result, Comp comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>,<br /></p>
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Proj1 proj1 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj2 proj2 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div>辅助类型</div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> I1, <span class="kw1">class</span> I2, <span class="kw1">class</span> O<span class="sy1">></span><br />
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<span class="kw1">using</span> set_union_result <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">in_in_out_result</span><span class="sy1"><</span>I1, I2, O<span class="sy1">></span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<p>构造始于 <code>result</code> 的，由来自一或两个已排序的输入范围 <code>[first1, last1)</code> 与 <code>[first2, last2)</code> 的元素组成的已排序范围。</p>
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<p>若在 <code>[first1, last1)</code> 中找到 <code>m</code> 次并在 <code>[first2, last2)</code> 中找到 <code>n</code> 次某元素，则将从 <code>[first1, last1)</code> 复制 <code>m</code> 个元素到 <code>result</code> ，保持顺序，然后将从 <code>[first2, last2)</code> 复制恰好 <span class="t-c"><span class="mw-geshi cpp source-cpp">max<span class="br0">(</span>n<span class="sy2">-</span>m, <span class="nu0">0</span><span class="br0">)</span></span></span> 个元素到 <code>result</code> ，亦保持顺序。</p>
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<p>若</p>
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<ul>
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<li>输入范围未分别按 <code>comp</code> 和 <code>proj1</code> 或 <code>proj2</code> 排序，或</li>
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<li>输入范围与输出范围重叠，</li>
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</ul>
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<p>则行为未定义。</p>
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<div class="t-li1"><span class="t-li">1)</span> 用给定的二元比较函数 <code>comp</code> 比较元素。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ，但以 <code>r1</code> 为第一范围并以 <code>r2</code> 为第二范围，如同以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r1<span class="br0">)</span></span></span> 为 <code>first1</code> ，以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r1<span class="br0">)</span></span></span> 为 <code>last1</code> ，以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r2<span class="br0">)</span></span></span> 为 <code>first2</code> 并以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r2<span class="br0">)</span></span></span> 为 <code>last2</code> 。</div>
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<p>此页面上描述的仿函数实体是 <i>niebloid</i> ，即：</p>
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<ul>
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<li>调用它们中的任何一者时不可指定显式模板实参。</li>
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<li>它们无一对<a href="cpp-language-adl.html">实参依赖查找</a>可见。</li>
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<li>在<a href="cpp-language-unqualified_lookup.html">通常无限定查找</a>寻找函数调用运算符左侧的名称找到它们之一时，它禁止<a href="cpp-language-adl.html">实参依赖查找</a>。</li>
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</ul>
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<p>实际上，它们能以函数对象，或以某些特殊编译器扩展实现。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin"></table>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>first1, last1</td>
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<td>-</td>
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<td>第一已排序输入范围</td>
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</tr>
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<tr class="t-par">
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<td>first2, last2</td>
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<td>-</td>
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<td>第二已排序输入范围</td>
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</tr>
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<tr class="t-par">
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<td>r1</td>
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<td>-</td>
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<td>第一已排序输入范围</td>
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</tr>
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<tr class="t-par">
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<td>r2</td>
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<td>-</td>
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<td>第二已排序输入范围</td>
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</tr>
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<tr class="t-par">
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<td>result</td>
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<td>-</td>
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<td>输出范围的起始</td>
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</tr>
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<tr class="t-par">
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<td>comp</td>
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<td>-</td>
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<td>应用到投影后元素的谓词</td>
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</tr>
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<tr class="t-par">
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<td>proj1</td>
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<td>-</td>
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<td>应用到第一范围元素的投影</td>
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</tr>
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<tr class="t-par">
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<td>proj2</td>
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<td>-</td>
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<td>应用到第二范围元素的投影</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">{</span>last1, last2, result_last<span class="br0">}</span></span></span> ，其中 <span class="t-c"><span class="mw-geshi cpp source-cpp">result_last</span></span> 为构造的范围的末尾。</p>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
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<p>至多比较和应用每个投影 <span class="mjax" style="display:none">\(\scriptsize 2\cdot(N_1+N_2)-1\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">2·(N<span class="t-su t-su-b"><br />
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1</span>+N<span class="t-su t-su-b"><br />
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2</span>)-1</span> 次，其中 <span class="mjax" style="display:none">\(\scriptsize N_1\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">N<span class="t-su t-su-b"><br />
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1</span></span> 与 <span class="mjax" style="display:none">\(\scriptsize N_2\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">N<span class="t-su t-su-b"><br />
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2</span></span> 分别为 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first1, last1<span class="br0">)</span></span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first2, last2<span class="br0">)</span></span></span> 。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>此算法进行与 <span class="t-lc">ranges::merge</span> 所做的类似的任务。两者都消费已排序的输入范围并产生拥有来自两个范围的元素的已排序输出。这两个算法间的区别是处理来自两个输入范围的比较等价的值（见<a href="cpp-named_req-LessThanComparable.html"><span style="font-style:italic">可小于比较</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LessThanComparable)</span></a> 上的注解）。若任何等价的值在第一范围中出现 <code>n</code> 次，在第二范围出现 <code>m</code> ，则 <span class="t-lc">ranges::merge</span> 将输出所有 <span class="t-c"><span class="mw-geshi cpp source-cpp">n<span class="sy2">+</span>m</span></span> 次出现，而 <code>ranges::set_union</code> 会只输出 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-algorithm-max.html"><span class="kw1640">std::<span class="me2">max</span></span></a><span class="br0">(</span>n, m<span class="br0">)</span></span></span> 次。故 <span class="t-lc">ranges::merge</span> 准确地输出 <span class="mjax" style="display:none">\(\scriptsize (N_1+N_2)\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">(N<span class="t-su t-su-b"><br />
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1</span>+N<span class="t-su t-su-b"><br />
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2</span>)</span> 个值，而 <code>ranges::set_union</code> 可能产生较少的值。</p>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">可能的实现</span></h3>
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<table class="eq-fun-cpp-table">
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="kw1">struct</span> set_union_fn <span class="br0">{</span>
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<span class="kw1">template</span><span class="sy1"><</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I1, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I1<span class="sy1">></span> S1,
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std<span class="sy4">::</span><span class="me2">input_iterator</span> I2, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I2<span class="sy1">></span> S2,
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std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O, <span class="kw1">class</span> Comp <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">less</span>,
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<span class="kw1">class</span> Proj1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>, <span class="kw1">class</span> Proj2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">mergeable</span><span class="sy1"><</span>I1, I2, O, Comp, Proj1, Proj2<span class="sy1">></span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">set_union_result</span><span class="sy1"><</span>I1, I2, O<span class="sy1">></span>
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operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> I1 first1, S1 last1, I2 first2, S2 last2,
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O result, Comp comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>,
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Proj1 proj1 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj2 proj2 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;</span> <span class="sy3">!</span><span class="br0">(</span>first1 <span class="sy1">==</span> last1 or first2 <span class="sy1">==</span> last2<span class="br0">)</span><span class="sy4">;</span> <span class="sy2">++</span>result<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="br0">(</span><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>comp, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj1, <span class="sy2">*</span>first1<span class="br0">)</span>,
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<a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj2, <span class="sy2">*</span>first2<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="sy2">*</span>result <span class="sy1">=</span> <span class="sy2">*</span>first1<span class="sy4">;</span> <span class="sy2">++</span>first1<span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">else</span> <span class="kw1">if</span> <span class="br0">(</span><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>comp, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj2, <span class="sy2">*</span>first2<span class="br0">)</span>,
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|
<a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj1, <span class="sy2">*</span>first1<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="sy2">*</span>result <span class="sy1">=</span> <span class="sy2">*</span>first2<span class="sy4">;</span> <span class="sy2">++</span>first2<span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">else</span> <span class="br0">{</span>
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<span class="sy2">*</span>result <span class="sy1">=</span> <span class="sy2">*</span>first1<span class="sy4">;</span> <span class="sy2">++</span>first1<span class="sy4">;</span> <span class="sy2">++</span>first2<span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span>
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<span class="kw4">auto</span> res1 <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">copy</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first1<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>last1<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> res2 <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">copy</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first2<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>last2<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>res1.<span class="me1">out</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="br0">{</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>res1.<span class="me1">in</span><span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>res2.<span class="me1">in</span><span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>res2.<span class="me1">out</span><span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">template</span><span class="sy1"><</span> ranges<span class="sy4">::</span><span class="me2">input_range</span> R1, ranges<span class="sy4">::</span><span class="me2">input_range</span> R2,
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std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O, <span class="kw1">class</span> Comp <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">less</span>,
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<span class="kw1">class</span> Proj1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>, <span class="kw1">class</span> Proj2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">mergeable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>, ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R2<span class="sy1">></span>,
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O, Comp, Proj1, Proj2<span class="sy1">></span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">set_union_result</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>,
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ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R2<span class="sy1">></span>, O<span class="sy1">></span>
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operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> R1<span class="sy3">&&</span> r1, R2<span class="sy3">&&</span> r2, O result, Comp comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>,
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Proj1 proj1 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj2 proj2 <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">return</span> <span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r1<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r1<span class="br0">)</span>,
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ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r2<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r2<span class="br0">)</span>,
|
|
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>comp<span class="br0">)</span>,
|
|
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>proj1<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>proj2<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
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<span class="br0">}</span>
|
|
<span class="br0">}</span><span class="sy4">;</span>
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|
|
|
<span class="kw1">inline</span> <span class="kw4">constexpr</span> set_union_fn set_union<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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|
<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <algorithm></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <iterator></span>
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<span class="co2">#include <vector></span>
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<span class="kw4">void</span> print<span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> in1, <span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> in2, <span class="kw4">auto</span> first, <span class="kw4">auto</span> last<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"{ "</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> e <span class="sy4">:</span> in1<span class="br0">)</span> <span class="br0">{</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> e <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span> <span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"} ∪ { "</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> e <span class="sy4">:</span> in2<span class="br0">)</span> <span class="br0">{</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> e <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span> <span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"} =<span class="es1">\n</span>{ "</span><span class="sy4">;</span>
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|
<span class="kw1">while</span> <span class="br0">(</span><span class="sy3">!</span><span class="br0">(</span>first <span class="sy1">==</span> last<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="sy2">*</span>first<span class="sy2">++</span> <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span> <span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"}<span class="es1">\n</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
|
|
<span class="br0">}</span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> in1, in2, out<span class="sy4">;</span>
|
|
|
|
in1 <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span>, <span class="nu0">5</span><span class="br0">}</span><span class="sy4">;</span>
|
|
in2 <span class="sy1">=</span> <span class="br0">{</span> <span class="nu0">3</span>, <span class="nu0">4</span>, <span class="nu0">5</span>, <span class="nu0">6</span>, <span class="nu0">7</span><span class="br0">}</span><span class="sy4">;</span>
|
|
out.<span class="me1">resize</span><span class="br0">(</span>in1.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> in2.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw4">const</span> <span class="kw4">auto</span> ret <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">set_union</span><span class="br0">(</span>in1, in2, out.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
print<span class="br0">(</span>in1, in2, out.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, ret.<span class="me1">out</span><span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
in1 <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span>, <span class="nu0">5</span>, <span class="nu0">5</span>, <span class="nu0">5</span><span class="br0">}</span><span class="sy4">;</span>
|
|
in2 <span class="sy1">=</span> <span class="br0">{</span> <span class="nu0">3</span>, <span class="nu0">4</span>, <span class="nu0">5</span>, <span class="nu0">6</span>, <span class="nu0">7</span><span class="br0">}</span><span class="sy4">;</span>
|
|
out.<span class="me1">clear</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
|
|
out.<span class="me1">reserve</span><span class="br0">(</span>in1.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> in2.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">set_union</span><span class="br0">(</span>in1, in2, <a href="cpp-iterator-back_inserter.html"><span class="kw665">std::<span class="me2">back_inserter</span></span></a><span class="br0">(</span>out<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
print<span class="br0">(</span>in1, in2, out.<span class="me1">cbegin</span><span class="br0">(</span><span class="br0">)</span>, out.<span class="me1">cend</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">{ 1 2 3 4 5 } ∪ { 3 4 5 6 7 } =
|
|
{ 1 2 3 4 5 6 7 }
|
|
|
|
{ 1 2 3 4 5 5 5 } ∪ { 3 4 5 6 7 } =
|
|
{ 1 2 3 4 5 5 5 6 7 }</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-set_difference.html"><span class="t-lines"><span>ranges::set_difference</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>计算两个集合的差集<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-set_intersection.html"><span class="t-lines"><span>ranges::set_intersection</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>计算两个集合的交集<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-set_symmetric_difference.html"><span class="t-lines"><span>ranges::set_symmetric_difference</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>计算两个集合的对称差<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-merge.html"><span class="t-lines"><span>ranges::merge</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>归并二个已排序范围<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-includes.html"><span class="t-lines"><span>ranges::includes</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>若一个序列是另一个的子列则返回 <code>true</code><br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-set_union.html"><span class="t-lines"><span>set_union</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>计算两个集合的并集<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
<table>
|
|
<tr>
|
|
<td></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
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|
</div>
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</div>
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</div>
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</body>
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</html>
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