【leetcode】第75题 Sort Colors 题目+解析+JAVA代码

【题目】

Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.

Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.

Note:
You are not suppose to use the library's sort function for this problem.

【解析】

这道题就是给了一个数组，其中都是乱序的0，1，2，让我们把乱序的0，1，2重新排列成0000……1111……2222.

这里用一个i来遍历数组，left和right分别保存0和2的边界，i在遍历过程中遇到0与left交换，遇到2与right交换。

【代码】

 public void sortColors(int[] nums) {        int left=0, right=nums.length-1;        int i=0;        while(i<=right){            if(nums[i]==1)                i++;            else if(nums[i]==0){                swap(nums,i,left);                left++;                i++;            }            else{                swap(nums,i,right);                right--;            }        }    }    public void swap(int[] nums,int m,int n){        int temp=nums[m];        nums[m]=nums[n];        nums[n]=temp;    }