zoukankan      html  css  js  c++  java
  • 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.
    

      

    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?
    

      于链表的双指针问题,这里也要track两个index,一个是red的index,一个是blue的index,两边往中间走。

    class Solution {
    public:
        void sortColors(int A[], int n) {
            // Start typing your C/C++ solution below
            // DO NOT write int main() function
            int zeroPos = 0;
            int twoPos = n-1;
            int i = 0;
            while(i<= twoPos){
                int temp;
                if(A[i] == 0){
                    temp = A[zeroPos];
                    A[zeroPos] = 0;
                    A[i] =  temp;
                    i++;zeroPos++;
                }else if(2 == A[i]){
                    temp = A[twoPos];
                    A[twoPos] = 2;
                    A[i] = temp;
                    twoPos--;
                }else
                     i++;
            }
        }
    };
  • 相关阅读:
    mysql类似oracle rownum写法
    mysql派生查询必须有别名问题记录
    MySQL逻辑架构简介
    JSON转成List结构数据
    MySQL锁表查询SQL
    Http请求传json数据中文乱码问题
    异步调用导致的不同步问题
    oracle导入Excel表文本数据
    JSP页面的注释细节
    Oracle cursor学习笔记
  • 原文地址:https://www.cnblogs.com/graph/p/3233434.html
Copyright © 2011-2022 走看看