75. Sort Colors

标签：wap   input   oid   repr   pass   str   using   span   The   

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?

•  1 class Solution {
   2     public void swap(int []nums, int l, int r) {
   3         int temp = nums[l];
   4         nums[l] = nums[r];
   5         nums[r] = temp;
   6     }
   7     public void sortColors(int[] nums) {
   8         int n = nums.length;
   9         int l = 0, r = n - 1;
  10         int i = 0;
  11         while (i >= l && i <= r && l <= r) {
  12             while (l <= r && nums[l] == 0) l++;
  13             while (l <= r && nums[r] == 2) r--;
  14             if (l > r) break;
  15             i = Math.max(i, l);
  16             if (nums[i] == 2) {
  17                 swap(nums, i, r--);
  18             } else if (nums[i] == 0) {
  19                 swap(nums, i, l++);
  20             } else {
  21                 i++;
  22             }
  23             
  24             
  25         }
  26         
  27     }
  28 }

   

75. Sort Colors

标签：wap   input   oid   repr   pass   str   using   span   The   

原文地址：https://www.cnblogs.com/hyxsolitude/p/12324386.html