排序

一、冒泡排序

原版冒泡

//原版冒泡排序
//从前向后遍历
//相邻两数比较，不满足顺序则交换
int[] arr= new int[10];
for (int i = 0; i < arr.length; i++) {
    arr[i] = (int)(Math.random()*100);
}
System.out.println(Arrays.toString(arr));
for (int i = 0; i < arr.length-1; i++) {
    for(int j =0;j< arr.length-1-i;j++){
        if(arr[j]>arr[j+1]){
            int temp = arr[j];
            arr[j]  = arr[j+1];
            arr[j+1] = temp;
        }
    }
}
System.out.println(Arrays.toString(arr));

优化后的冒泡

//优化过后的冒泡排序
int[] arr= new int[10];
for (int i = 0; i < arr.length; i++) {
    arr[i] = (int)(Math.random()*100);
}
System.out.println(Arrays.toString(arr));
boolean isChanged = false;      //当内层循环没变时候，即没有交换则已经有序，所以停止
for (int i = 0; i < arr.length-1; i++) {
    for(int j =0;j< arr.length-1-i;j++){
        isChanged = true;
        if(arr[j]>arr[j+1]){
            int temp = arr[j];
            arr[j]  = arr[j+1];
            arr[j+1] = temp;
        }
    }
    if(!isChanged)
        System.out.println(i);
        break;
}
System.out.println(Arrays.toString(arr));

二、选择排序

//外层循环控制第几个位置
//内层循环确定该位置的值
int[] arr= new int[10];
for (int i = 0; i < arr.length; i++) {
    arr[i] = (int)(Math.random()*100);
}
System.out.println(Arrays.toString(arr));
for (int i = 0; i < arr.length-1; i++) {
    int temp = arr[i];          //用于交换
    int pos = i;                //记录要交换的元素下标
    for(int j = i+1; j<arr.length; j++){
        if(temp>arr[j]){
            temp = arr[j];      //temp用于暂存要交换的值
            pos = j;
        }
    }
    arr[pos] = arr[i];          //遍历完一遍后在交换
    arr[i] = temp;
}
System.out.println(Arrays.toString(arr));

三、插入排序

int[] arr= new int[10];
for (int i = 0; i < arr.length; i++) {
    arr[i] = (int)(Math.random()*100);
}
System.out.println(Arrays.toString(arr));
for(int i =1;i<arr.length;i++){
    int temp = arr[i];
    boolean isInsert = false;
    for(int j =i-1;j>=0;j--){
        if(arr[j]>temp){
            arr[j+1] = arr[j];
        }else {
            arr[j+1] = temp;
            isInsert = true;
            break;
        }
    }
    if(!isInsert){
        arr[0] = temp;
    }
}
System.out.println(Arrays.toString(arr));

持续更新中…

本文地址：https://blog.csdn.net/qq_43288259/article/details/112586467