class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int start = 0, end = nums.size(),ans=0;
        while(start < end)  {
            if(nums[start] == val)  {
                swap(nums[start],nums[end-1]);
                end--;
            }    
            else start++;
        }
        return end;
    }
};