27-75. Sort Colors

题目描述：

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?

代码实现：

 1 def sortColors(self, nums):
 2     i = j = 0
 3     for k in xrange(len(nums)):
 4         v = nums[k]
 5         nums[k] = 2
 6         if v < 2:
 7             nums[j] = 1
 8             j += 1
 9         if v == 0:
10             nums[i] = 0
11             i += 1

原文地址：https://www.cnblogs.com/tbgatgb/p/11043147.html