leetcode Remove Duplicates from

题目

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.
Do not allocate extra space for another array, you must do this in place with constant memory.

For example,
Given input array A = [1,1,2],
Your function should return length = 2, and A is now [1,2].

解题思路：

用两个指针，一个指针指向结果数组，一个指针遍历数组。

代码：

public int removeDuplicates(int[] A) {  
        if (A.length == 0 || A == null)  
            return 0;  
        int i = 0;  
        int j = 1;  
        while (j < A.length) {  
            if (A[j] == A[i])  
                j++;  
            else  
                A[++i] = A[j++];  
        }  
        return i + 1;  
    }