class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        if(nums.size() == 0) {
            return 0;
        }
        int fast=0,slow=0;
        while(fast < nums.size()) {
            if(nums[fast] != val) {
                nums[slow] = nums[fast];
                slow++;
            }
            fast++;
        }
        return slow;
    }
};