https://mem.leabol.top/tags/%E5%8F%8C%E6%8C%87%E9%92%88/ Recent content in 双指针 on memory Hugo zh-cn Thu, 11 Jun 2026 00:00:00 +0000 https://mem.leabol.top/posts/dsa/double_pointer/ Thu, 11 Jun 2026 00:00:00 +0000 https://mem.leabol.top/posts/dsa/double_pointer/ <h1 id="双指针">双指针</h1> <h2 id="快慢指针">快慢指针</h2> <h4 id="删除有序数组中的重复项">删除<strong>有序</strong>数组中的重复项</h4> <blockquote> <p>一个有序数组nums，原地删除重复出现的元素，使得出现次数超过两次的元素只出现两次 ，返回删除后数组的新长度</p></blockquote> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-cpp" data-lang="cpp"><span style="display:flex;"><span><span style="color:#66d9ef">int</span> <span style="color:#a6e22e">removeDuplicates</span>(vector<span style="color:#f92672">&lt;</span><span style="color:#66d9ef">int</span><span style="color:#f92672">&gt;&amp;</span> nums) { </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">int</span> n <span style="color:#f92672">=</span> nums.size(); </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> (n <span style="color:#f92672">&lt;=</span> <span style="color:#ae81ff">2</span>) { </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> n; </span></span><span style="display:flex;"><span> } </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">int</span> slow <span style="color:#f92672">=</span> <span style="color:#ae81ff">2</span>; </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">for</span> (<span style="color:#66d9ef">int</span> fast <span style="color:#f92672">=</span> <span style="color:#ae81ff">2</span>; fast <span style="color:#f92672">&lt;</span> n; <span style="color:#f92672">++</span>fast){ </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">if</span> (nums[fast] <span style="color:#f92672">!=</span> nums[slow<span style="color:#f92672">-</span><span style="color:#ae81ff">2</span>]){<span style="color:#75715e">// fast 是读指针，不是写指针。我们无法知道前面已经写了多少个相同的值。只有 slow 才能记录我们已经保留了多少个相同的值。 </span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span> nums[slow<span style="color:#f92672">++</span>] <span style="color:#f92672">=</span> nums[fast]; </span></span><span style="display:flex;"><span> } </span></span><span style="display:flex;"><span> } </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">return</span> slow; </span></span><span style="display:flex;"><span> } </span></span></code></pre></div><h4 id="移除元素">移除元素</h4> <blockquote> <p>在数组中,原地移除所有数值等于val的元素</p>