27. 移除元素

public int removeElement(int[] nums, int val) {

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

    return idx;
}

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

        int idx = 0;
        int last = nums.length;

        while (idx < last) {
            if (nums[idx] == val) {
                nums[idx] = nums[last - 1];
                last--;
            } else {
                idx++;
            }
        }

        return idx;
    }
}