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Update 0027.移除元素.md
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
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@ -106,6 +106,37 @@ public:
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旧文链接:[数组:就移除个元素很难么?](https://programmercarl.com/0027.移除元素.html)
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```CPP
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/**
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* 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
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* 时间复杂度:$O(n)$
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* 空间复杂度:$O(1)$
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*/
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class Solution {
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public:
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int removeElement(vector<int>& nums, int val) {
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int leftIndex = 0;
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int rightIndex = nums.size() - 1;
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while (leftIndex <= rightIndex) {
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// 找左边等于val的元素
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while (leftIndex <= rightIndex && nums[leftIndex] != val){
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++leftIndex;
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}
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// 找右边不等于val的元素
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while (leftIndex <= rightIndex && nums[rightIndex] == val) {
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-- rightIndex;
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}
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// 将右边不等于val的元素覆盖左边等于val的元素
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if (leftIndex < rightIndex) {
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nums[leftIndex++] = nums[rightIndex--];
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}
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}
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return leftIndex; // leftIndex一定指向了最终数组末尾的下一个元素
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}
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};
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```
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## 相关题目推荐
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* 26.删除排序数组中的重复项
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