Remove Duplicates from Sorted Array

1.问题描述

LeetCode：
Remove Duplicates from Sorted Array 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].

2.问题分析

已完成排序的数组去重，要求空间复杂度为O(1)。

使用两个索引，其中一个依次指向数组的每一个元素；另一个索引指向非重复的数字。

3.代码

//时间复杂度O(n),空间复杂度O(1)
#include "stdio.h"
#include <iostream>
using namespace std;
class Solution
{
public:
	int removeDuplicates(int A[], int n)
	{
		if(n == 0) return 0;

		int index = 0;
		for(int i = 1; i < n; ++i)
		{
			if(A[index] != A[i])
				A[++index] = A[i];		
		}
		return index + 1;
	}
};

//测试
int main(int argc, char* argv[])
{
	Solution A;
	int b[5] = {1,2,2,3,3};
	int length = A.removeDuplicates(b,5);
	cout << length << endl;
	system("pause");
	return 0;

}

4.总结

不开辟另外的数组，在原数组上进行去重，需要使用两个索引进行去重。