LeetCode——Sort Colors

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.

click to show follow up.

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 an one-pass algorithm using only constant space?

原题链接：https://oj.leetcode.com/problems/sort-colors/

题目：给定一个数组，有n个对象，其中有红色，白色，蓝色，将他们排序，使得相同的颜色相邻，结果为红 白 蓝这样的顺序。

这里分别用0 1 2 代表红 白 蓝。

	public void sortColors(int[] A) {
		int len = A.length;
		int index = -1;
		for (int i = 0; i < len; i++) {
			if (A[i] == 0) {
				index++;
				swap(A, i, index);
			}
			if (A[i] == 2) {
				len--;
				swap(A, i, len);
				i--;
			}
		}
	}

	private void swap(int[] A, int i, int j) {
		int tmp = A[i];
		A[i] = A[j];
		A[j] = tmp;
	}

LeetCode——Sort Colors