二分查找(java实现)

package com.algorithms;

public class BinarySearch {
/**
*  numbers 有序数组
*  key 被查找的元素
*  return 未找到的话返回-1
* 算法复杂度O(logN)
**/
public static int keyPosition(int[] numbers,int key) {
    int high=numbers.length-1;
    int low=0;
    while(low<=high){
        int mid=low+(high-low)/2;
        if (key>numbers[mid]) {
            low=mid+1;
        }else if (key<numbers[mid]) {
            high=mid-1;
        }else {
            return mid;
        }
    }
    return -1;
}
public static void main(String[] args) {
    System.out.println(keyPosition(new int[]{1,2,3,4,5},3));
}
}