package com.zdcf.leetcode;
//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:
//
//        A rather straight forward solution is a two-pass algorithm using counting sort.
//        First, iterate the array counting number of 0's, 1's, and 2's, then overwrite array with total number of 0's, then 1's and followed by 2's.
//        Could you come up with a one-pass algorithm using only constant space?
public class SortColors {

    //思想是优化的快排,O(N)

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

            }else{
                temp = nums[right];
                nums[right] = nums[i];
                nums[i] = temp;
                right--;
            }
    }
}