原题链接: https://oj.leetcode.com/problems/remove-duplicates-from-sorted-array/

public int removeDuplicates(int[] A) {
    if (A == null || A.length == 0) return 0;

    int index = 1;

    for (int i = 1, length = A.length; i < length; i++) {
        if (A[i] != A[i - 1]) {
            A[index] = A[i];
            index++;
        }
    }

    return index;
}