二分查找

package com.sly.uploadfile.algorithm.pack1;

import java.util.Arrays;

/**
 * Created by fmgao on 2019/9/25.
 * <p>
 * Java语言二分查找代码实现
 */
public class ErFenChaZhao {

    /**
     * 二分查找key值对应的下标
     *
     * @param source 输入的源数组 ，请保证为一个有序数组
     * @param key    需要查找的值
     * @return 正数为查找到的坐标，-1表示没有查到
     */
    public static int binarySearch(int[] source, int key) {
        int low = 0;
        int high = source.length - 1;
        while (low <= high) {
            int mid = (low + high) >>> 1; //使用位移运算法高效地获取折中下标，这里不考虑符号，所以使用>>>
            int midVal = source[mid];
            if (midVal < key) {
                low = mid + 1;
            } else if (midVal > key) {
                high = mid - 1;
            } else
                return mid;
        }
        return -1;
    }

    public static void main(String[] args) {
        int[] source = new int[]{12, 213, 232, 343, 123, -1, 123, 232424, 1253, 56, 456, 234, -2342};
        //保证数组为有序数组
        Arrays.sort(source);
        //打印排序后的数组元素
        System.out.print("Sorted Source : ");
        for (int i = 0; i < source.length; i++) {
            System.out.print(source[i] + " ");
        }
        System.out.println();
        System.out.println(binarySearch(source, 56));
    }

}

二分查找

原文：https://www.cnblogs.com/fmgao-technology/p/13169139.html