java 二分查找

摘要: java 二分查找 递归/非递归

/**

* Created by 737597978 on 2015/5/23.

*/

public class BinarySearch {

//常规循环方法

public static int binarySearch(int [] array,int key){

int low=0;

int high=array.length-1;

int mid;

while (low<=high){

mid=(low+high)/2;

if(array[mid]==key){

return mid;

}

if(array[mid]>key){

high=mid-1;

}else{

low=mid+1;

}

}

return -1;

}

//递归方式

public static int recursiveBinarySearch(int [] array,int low,int high ,int key){

if(low<=high){

int mid=(low+high)/2;

if(array[mid]==key){

return mid;

}else if(key>array[mid]){

recursiveBinarySearch(array,mid+1,high,key);

}else{

recursiveBinarySearch(array,low,mid-1,key);

}

}

return -1;

}

public static void main(String[] args) {

int [] test={1,2,3,5,19,20,23,49,50,51,60,89,100,123,124};

//int index=BinarySearch.binarySearch(test,49);

int index=BinarySearch.recursiveBinarySearch(test,0,test.length-1,49);

System.out.println(index);

}

}