Java算法关于二分查找法的示例讲解

package me.geed.algorithms; public class BinarySearch { /** * 从一个有序数组(如升序)中找到值为key元素 * @param key * @param array * @return 如果找到目标元素，则返回其在数组中的索引，否则返回-1 */ public static int find(int key, int[] array){ int low = 0; int high = array.length - 1; while (low <= high) { int mid = low + (high - low) / 2; if (array[mid] > key) { high = mid - 1; } else if (array[mid] < key) { low = mid + 1; } else { return mid; } } return -1; } public static void main(String[] args) { // TODO Auto-generated method stub int[] array = {2, 3, 5, 9, 10, 13, 23, 45, 78, 89, 100, 128, 256}; System.out.println("目标元素索引值：" + BinarySearch.find(9, array)); System.out.println("目标元素索引值：" + BinarySearch.find(26, array)); } }

目标元素索引值：3 目标元素索引值：-1