排序算法

Posted 2021-11-29 cn-chy-com

/**
 * 冒泡排序
 * @param arr
 */
public static void bubbleSort(int [] 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;
            }
        }
    }
}

/**
 * 二分查找
 * @param arr
 * @param x
 * @return
 */

public static int find(int [] arr,int x){
    int min = 0;
    int max = arr.length - 1;
    int mid = (min + max)/2;
    while(arr[mid] != x){
        if(arr[mid] > x){
            max = mid -1;
        }
        if(arr[mid] <x){
            min = mid + 1;
        }
        mid = (min + max)/2;
        if(min > max){
            return -1;
        }
    }
    return mid;
}

/**
 * 快速排序
 * @param arr
 * @param low
 * @param high
 */
public static void quickSort(int [] arr,int low,int high){
    int i,j,index;
    if(low >= high){
        return;
    }
    i = low;
    j = high;
    index = arr[i];
    while (i < j){
        while(i < j && arr[j] >= index){
            j--;
        }
        if(i < j){
            arr[i++] = arr[j];
        }
        while (i < j && arr[i] <= index){
            i++;
        }
        if(i < j){
            arr[j--] = arr[i];
        }
        arr[i] = index;
        quickSort(arr,low,i-1);
        quickSort(arr,i+1,high);
    }
}