【LeeCode】排序算法

选择排序

import java.util.*;
/**
 * 选择排序
 */

public class Main {
    public static void main(String[] args) {
        int[] arr = {12, 2, 33, 1, 21, 3, 11, 3};
        System.out.println("初始值" + Arrays.toString(arr));
        xuanze(arr);
    }

    private static void xuanze(int[] arr) {

        for(int i = 0; i < arr.length; i++){
            for(int j = i; j < arr.length; j++){
                if(arr[i] > arr[j]){
                    int tmp = arr[j];
                    arr[j] = arr[i];
                    arr[i] = tmp;
                }
            }
        }
        System.out.println("选择：" + Arrays.toString(arr));
    }
}

冒泡排序

import java.util.*;
/**
 * 冒泡排序
 */

public class Main {
    public static void main(String[] args) {
        int[] arr = {12, 2, 33, 1, 21, 3, 11, 3};
        System.out.println("初始值" + Arrays.toString(arr));
        maopao(arr);
    }

    private static void maopao(int[] arr) {

        for(int i = 0; i < arr.length; i++){
            for(int j = 0; j < arr.length - 1; j++){
                if(arr[j] > arr[j+1]){
                    int tmp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = tmp;
                }
            }
        }
        System.out.println("冒泡：" + Arrays.toString(arr));
    }
}

快速排序

import java.util.*;
/**
 * 快速排序
 */

public class Main {
    public static void main(String[] args) {
        int[] arr = {12, 2, 33, 1, 21, 3, 11, 3};
        kuaisu(arr, 0, arr.length-1);
        System.out.println(Arrays.toString(arr));
    }

    private static void kuaisu(int[] arr, int low, int high) {
        int i,j,tmp;
        if(low > high){
            return;
        }

        i = low;
        j = high;
        tmp = arr[low];

        while (i < j ){
            while (tmp <= arr[j] && i < j ){
                j--;
            }

            while (tmp >= arr[i] && i < j ){
                i++;
            }

            if( i < j ) {
                int x = arr[i];
                int y = arr[j];
                arr[i] = y;
                arr[j] = x;
            }
        }

        // i == j , 交换第一轮的基准值到它应该的位置
        arr[low] = arr[i];
        arr[i] = tmp;

        kuaisu(arr, low, j-1);
        kuaisu(arr, j+1, high);

    }
}