Solution.cpp

class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int cnt = 0, n = nums.size();
        for (int i = 0; i < n; ++i) {
            if (nums[i] == val) ++cnt;
            else nums[i - cnt] = nums[i];
        }
        return n - cnt;
    }
};