Java实现二分查找具体实现代码

Posted 2021-06-28 g0rez

import java.util.Arrays;

/**
 *使用二分法查找的前提是数组中的元素已排序好
 *@author g0rez
 *@data 2021-06-17
 *
 */
public class 二分法查找 {
    public static void main(String[] args) {
        int[] arr =new int[]{100,200,599,201,355};
        Arrays.sort(arr);
        for (int j = 0; j <arr.length ; j++) {
            System.out.print(arr[j]+" ");
        }
        System.out.println();
        System.out.println(binarySearch(arr,201));
        //这里与Arrays类中已经实现的二分查找方法输出结果进行对比
        System.out.println(Arrays.binarySearch(arr,201));
    }

    public static int binarySearch(int[] arr,int dest) {
        int begin=0;
        int end=arr.length-1;
        while (begin<=end){
            int mid=(begin+end)/2;
            if(arr[mid]==dest){
                    return mid;
            }else if(arr[mid]>dest){
                end=mid-1;
            }else {
                begin=mid+1;
            }
        }
        return -1;

    }

}

运行结果