class Solution {
public:
    int removeDuplicates(vector<int>& nums) {
        int length = nums.size();
        int index = 1;

        if (length == 0)
            return 0;

        for(int i=1; i<length; i++) {
            if (nums[i] != nums[i-1])
                nums[index++] = nums[i];
        }

        return index;
    }
};