二分法查找
package com.execlib.search;
/**
* 二分法查找
*/
public class BinarySearch {
public int search(int[] data,int key){
return binarySearch(data,key,0,data.length-1);
}
public int binarySearch(int[] data,int key, int left, int right) {
if (left>=right)
return -1;
int mid = (left+right)/2;
if (data[mid]>key){
right = mid-1;
}else if (data[mid]<key){
left = mid+1;
}else {
System.out.println("找到数据：index="+mid);
return mid;
}
return binarySearch(data,key,left,right);
}
/**
* 非递归形式二分查找
* @param data
* @param key
* @return
*/
public int binarySearchNoCycle(int[] data,int key) {
int left = 0;
int right = data.length-1;
int mid = 0 ;
while (left<=right){
mid = (left+right)/2;
if (data[mid]>key){
right = mid-1;
}else if (data[mid]<key){
left = mid+1;
}else {
System.out.println("找到数据：index="+mid);
return mid;
}
}
return -1;
}
}
