Leetcode：Remove Duplicates from Sorted Array

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].

我的解法

一开始我忽略掉sorted array这个条件，所以导致我需要进行循环遍历，时间复杂度为O(n2)。结果就是在提交代码后提示：TimeLimitExceeded！

我的错误代码：

int removeDuplicates(int A[], int n) {    int i, j, num, mark;    num = 0;    for (i = 0; i < n; i++){        mark = 0;        for (j = 0; j < num; j++){            if (A[j] == A[i])                mark++;            else                ;        }        if (mark > 0)            ;        else            A[num++] = A[i];    }    return num;}

修改后的代码：

【和Remove Element那道题思路一致，采用双指针！！】

int removeDuplicates(int A[], int n) {    int i, num;    num = 1;    if (n < 2)        return n;    for (i = 1; i < n; i++){        if (A[i] != A[i - 1])            A[num++] = A[i];    }    return num;}