双指针
设置left =0,为保证单一出口
class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int n = nums.size();
int left = 0, right = 1; // left可覆盖的位置,right扫描指针
if(n == 0){
left =-1;
}
while(right<n){
if(nums[left]!=nums[right]){
left++;
nums[left]=nums[right];
}
right++;
}
return left+1;
}
};