Leetcode#26. 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 nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively. It doesn’t matter what you leave beyond the new length.

题意

给你一个已经排序好的数组，要求去掉相同的元素保留一个，写出一个函数返回新数组的个数。

注意点

• Do not allocate extra space for another array, you must do this in place with constant memory.
  不要为另一个数组分配额外的空间，您必须使用常量内存来执行此操作。
  刚开始我只是以为求出新数组的个数就可以了，竟然wrong answer，后来看了运行结果才发现，题意运行出来的结果的新数组，而不是个数。

思路

将原数组两用。

C++语言

class Solution {
public:
    int removeDuplicates(vector<int>& nums) {

        int res=0;
        if(nums.size()==0)
            return 0;

        for(int i =1; i<nums.size(); i++)
        {
           if(nums[res]!=nums[i])
           {    
               res+=1;
               nums[res] = nums[i];
           }    
        }
        return res+1;
    }
};

Python语言

class Solution(object):
    def removeDuplicates(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if len(nums)==0:
            return 0

        res = 0
        for i in range(0,len(nums)):
            if nums[res]!=nums[i]:
                res = res + 1
                nums[res]=nums[i]
        return res+1