/**
 * @param {number[]} nums
 * @param {number} val
 * @return {number}
 */
var removeElement = function(nums, val) {
    let fast = slow = 0;
    while(fast<nums.length){
        if(nums[fast] !== val){
            nums[slow] = nums[fast];
            slow++;
        }
        fast++
    }
    return slow
};