标签：output int str targe 了解 star could iter note
75. Sort Colors
Given an array with n objects colored red, white or blue, sort them in-place 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.
Example:
Input: [2,0,2,1,1,0] Output: [0,0,1,1,2,2]
Follow up:
题目Follow up 既然已经这么大方的给出了解题思路，那就先实现一遍再说。
基本思想是，使用三个变量，先遍历一次数组，记下0，1，2出现的次数，然后根据第一次遍历的结果，为原数组赋上对应的值，代码如下：
public void sortColors(int[] nums) { int[] countColors = new int[3]; for(int i : nums){ switch(i){ case 0: countColors[0]++; break; case 1: countColors[1]++; break; case 2: countColors[2]++; break; } } int start = 0; while(countColors[0]-- > 0){ nums[start++] = 0; } while(countColors[1]-- > 0){ nums[start++] = 1; } while(countColors[2]-- > 0){ nums[start++] = 2; } }
空间占用更少的解法，可以设置2个指针，在遍历的同时遇到0，则将当前元素和指向数组头的指针元素交换，同时指针加一，同理遇到2则和数组尾元素交换位置。代码如下：
public void sortColors(int[] nums) { int index = 0, pLeft = 0, pRight = nums.length - 1; while(index <= pRight){ if( 0 == nums[index]){ nums[index] = nums[pLeft]; nums[pLeft] = 0; pLeft++; index++; } else if(2 == nums[index]){ nums[index] = nums[pRight]; nums[pRight] = 2; pRight--; } else{ index++; } } }
标签：output int str targe 了解 star could iter note
原文地址：https://www.cnblogs.com/lyInfo/p/9113666.html
