1.背景

面试中经常问到算法相关的问题,今天给大家演示一下二分查找算法..

2.代码

package com.ldp.algorithm.demo01;

import org.junit.Test;

/**
 * @create 05/15 9:53
 * @description <p>
 * 二分查找算法
 * </p>
 */
public class Test01 {
    @Test
    public void test01() {
        int[] array = {1, 5, 45, 69, 200, 905, 906};
        System.out.println(binarySearch(array, 1));
        System.out.println(binarySearch(array, 906));
        System.out.println(binarySearch(array, 45));
        System.out.println(binarySearch(array, 2));
    }

    /**
     * 二分查找算法
     * 二分查找算法需要对已排序的数组进行操作
     *
     * @param array
     * @param key
     * @return
     */
    public int binarySearch(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;
        int middle;
        while (left <= right) {
            middle = (left + right) / 2;
            if (key == array[middle]) {
                return middle;
            } else if (key < array[middle]) { // 向左查找
                right = middle - 1;
            } else if (key > array[middle]) { // 向右查找
                left = middle + 1;
            }
        }
        return -1;
    }
}

完美!

标签：二分,int,binarySearch,程序员,算法,查找,array
来源： https://www.cnblogs.com/butingxue/p/16294839.html