java二分查找

package com.alo.offer;/** * 非递归的二分查找 * 适用于已经排序好的数组进行查找 * @author Administrator * */public class BinarySearch{public static void main(String[] args) {int []a= {1,5,9,17,56,89,123,257,368,489,578,684,784,857,942};System.out.println(new BinarySearch().searchNoRecur(a, 9));System.out.println(new BinarySearch().search(a, 9, 0, a.length-1));}public int searchNoRecur(int []a,int x) {int low=0,high=a.length-1;int mid=0;while(low<=high) {mid=low+(high-low)/2;if(x==a[mid]) {return mid;}else if(x>a[mid]){low=mid+1;}else {high=mid-1;}}return -1;}public int search(int []a,int x,int low ,int high) {if(low>high) return -1;int mid =low+(high-low)/2;if(a[mid]==x) {return mid;}else if(x>a[mid]){return search(a,x,mid+1,high);}else {return search(a,x,low,mid-1 );}}}