zoukankan      html  css  js  c++  java
  • [leetcode] 题型整理之排序

    75. 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.

    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?

    public class Solution {
        public void sortColors(int[] nums) {
            int length = nums.length;
            int bluePos = length - 1;
            while (bluePos >= 0 && nums[bluePos] == 2) {
                bluePos--;
            }
            int redPos = 0;
            while (redPos <= bluePos && nums[redPos] == 0) {
                redPos++;
            }
            for (int i = redPos; i <= bluePos; i++) {
                int x = nums[i];
                if (x == 2) {
                    if (i == bluePos) {
                        break;
                    } else {
                        nums[i] = nums[bluePos];
                        nums[bluePos] = 2;
                        while (bluePos >= redPos && nums[bluePos] == 2) {
                            bluePos--;
                        }
                        i--;
                    }
                } else if (x == 0) {
                    if (i == redPos) {
                        redPos++;
                    } else {
                        nums[i] = nums[redPos];
                        nums[redPos] = 0;
                        while (redPos <= bluePos && nums[redPos] == 0) {
                            redPos++;
                        }
                    }
                }
            }
        }
    }
  • 相关阅读:
    Python解析excel文件并存入sqlite数据库
    python简单爬虫
    Python开发简单记事本
    Django初体验——搭建简易blog
    LeetCode — (1)
    机器学习(九)—FP-growth算法
    机器学习(八)—Apriori算法
    linux下debug工具
    linux同步与通信
    后台开发之IO缓冲区管理
  • 原文地址:https://www.cnblogs.com/Gryffin/p/6231507.html
Copyright © 2011-2022 走看看