【LeetCode】26. Remove Duplicates from Sorted Array

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.

提示：

此题要求不能使用额外的内存空间，因此我们需要在原始数组上进行操作，对于这类问题，通常可以用“一快一慢双指针”的方法去解决，下面的代码很简单易懂。

代码：

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