From fc1a7e3e079958e6919bbc4fbe069a8d92e66322 Mon Sep 17 00:00:00 2001
From: zhaoninge <zhaoninge@126.com>
Date: Thu, 10 Feb 2022 17:01:31 +0800
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添加27. 移除元素 C++版相向双指针方法，该方法基于元素顺序可以改变的题目描述，使用双指针法改变了元素相对位置，确保了移动最少元素
---
 problems/0027.移除元素.md | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/problems/0027.移除元素.md b/problems/0027.移除元素.md
index d69f2bcf..0c6f5129 100644
--- a/problems/0027.移除元素.md
+++ b/problems/0027.移除元素.md
@@ -106,6 +106,37 @@ public:
 
 旧文链接：[数组：就移除个元素很难么？](https://programmercarl.com/0027.移除元素.html)
 
+```CPP
+/**
+* 相向双指针方法，基于元素顺序可以改变的题目描述改变了元素相对位置，确保了移动最少元素
+* 时间复杂度：$O(n)$
+* 空间复杂度：$O(1)$
+*/
+class Solution {
+public:
+    int removeElement(vector<int>& nums, int val) {
+        int leftIndex = 0;
+        int rightIndex = nums.size() - 1;
+        while (leftIndex <= rightIndex) {
+            // 找左边等于val的元素
+            while (leftIndex <= rightIndex && nums[leftIndex] != val){
+                ++leftIndex;
+            }
+            // 找右边不等于val的元素
+            while (leftIndex <= rightIndex && nums[rightIndex] == val) {
+                -- rightIndex;
+            }
+            // 将右边不等于val的元素覆盖左边等于val的元素
+            if (leftIndex < rightIndex) {
+                nums[leftIndex++] = nums[rightIndex--];
+            }
+        }
+        return leftIndex;   // leftIndex一定指向了最终数组末尾的下一个元素
+    }
+};
+```
+
+  
 ## 相关题目推荐
 
 * 26.删除排序数组中的重复项