算法-二分查找-非递归

package datastructure.binarysearch;

import java.util.ArrayList;

public class BinarySearch {

    public static void main(String[] args) {
        int[] array = {1,3,4,5,6,7,8,23,34,100};
        int i = binarySearch3(array, 100);
        System.out.println(i);

    }
    /**
     *
     * @param arr     升序数组
     * @param target   要找的数
     * @return       返回这个数的索引，没找到返回-1
     */


    public static int binarySearch3(int[] arr, int target) {
        int left = 0;
        int right = arr.length - 1;
        while(left <= right) {//退出的条件
            int mid = (left + right) / 2;
            if(arr[mid] == target) {
                return mid;
            }else if(arr[mid] < target) {
                left = mid + 1;
            }else {
                right = mid - 1;
            }
        }
        return -1;
    }
}