二分法查找

package com.abstractdatatype.search;/*二分法查找*/public class BinarySearch {public static void main(String[] args) {int [] a=new int [] {1,2,3,4,5,7,8,9}; int index=BinarySearch.binarySearch(a, 7);System.out.println(index);}/*Performs the standard binary search * @return index where item is found, or -1 if not found  * */public static int binarySearch(int [] a,int target){final int NOT_FOUND=-1;int low=0;int high=a.length-1;while(low<high){int mid=(low+high)/2;if(a[mid]<target){low=mid+1;}else if(a[mid]>target){high=mid-1;}else{return mid;}}return NOT_FOUND;}}