1. 题目

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this in place with constant memory.

For example,
Given input array nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively. It doesn’t matter what you leave beyond the new length.

2. 思路

遍历，维护两个下标，一个是待填充，一个是待处理。当待处理的与上一个相同时直接跳过，不同则移到待填充处。O(N),原地。

3. 代码

耗时：29ms

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