26 Remove Duplicates from Sorted Array

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.

Solution:

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

Notes
Practice again, thinking about the loop condition carefully.