https://leetcode.com/problems/remove-element/description/

解題思路：

1. nums[res++] == nums[i] when nums[i] == val;

代碼：
class Solution {
public int removeElement(int[] nums, int val) {

    if(nums == null) return 0;
    int res = 0;
    for(int i = 0; i < nums.length; i++){
        if(nums[i] != val)
            nums[res++] = nums[i];    
    }
    return res;
}

}