#折半查找 --- 基本原理：每次查找都對半分，但要求數組是有序的 ``` public class Solution { public static int BinarySearch(int[] sz,int key){ int low = 0; int high = sz.length - 1; while (low <= high) { int middle = (low + high) / 2; if(sz[middle] == key){ return middle; }else if(sz[middle] > key){ high = middle - 1; }else { low = middle + 1; } } return -1; } } ```