Remove Element

题目

Given an array and a value, remove all instances of that value in place and return the new length.

The order of elements can be changed. It doesn't matter what you leave beyond the new length.

方法

使用左右两个标记。

    public int removeElement(int[] A, int elem) {
        if (A == null || A.length == 0) {
            return 0;
        }
        int len = A.length;
        int left = 0;
        int right = len - 1;
        while (left < right) {
            while (left < right && A[left] != elem) {
                left++;
            }
            while(left < right && A[right] == elem) {
                right--;
            }
            if (left < right) {
                int temp = A[left];
                A[left] = A[right];
                A[right] = temp;
            }
        }
        if (A[left] != elem) {
        	left = left + 1;
        }
        return left;
    }