leetcode.27. Remove Element

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