题意：在有序数组中删除重复元素

https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/

解法：双指针,i记录答案，j遇到重复的值就往后跳过

class Solution {
public:int removeDuplicates(vector<int>& nums) {int i = 0;for(int j = 0; j < nums.size(); j++) {while (j > 0 && j < nums.size() && nums[j] == nums[j-1]) {j++;} if(j < nums.size()) {nums[i++] = nums[j];}}return i;}
};

解法二：双指针，但是判断的条件是略有不同，是判断j指向元素和i指向元素是否重复，代码更为简洁

class Solution {public:int removeDuplicates(vector<int>& a) {int i = 0;for (int j = 0; j < a.size(); j++)if (!i || a[j] != a[i - 1]) a[i++] = a[j];return i;}
};

时间复杂度$O(n)$
空间复杂度$O(1)$