二分查找（递归、非递归）

二分查找（递归）

package com.tao.algorithm;

/**
* Created by michael on 17-8-13.
*/
public class 二分查找_递归 {

public static void main(String[] args) {

int[] a = new int[] {1,2,3,4,5,6,7,8,9,10,11,12,13,14};

for(int i = 0; i < a.length; i++) {
int index = binSearch(a, 0, a.length-1, a[i]);
System.out.println(index);
}
}

/**
* 二分查找（递归）
* @param array
* @param start
* @param end
* @param key
* @return
*/
public static int binSearch(int[] array, int start, int end, int key) {

if(start <= end) {
int mid = (start+end)/2;
if(key == array[mid]){
return mid;
} else if(key < array[mid]) {
return binSearch(array, start, mid-1, key);
} else {
return binSearch(array, mid+1, end, key);
}
} else {
return -1;
}
}
}

二分查找（非递归）

package com.tao.algorithm;

/**
* Created by michael on 17-8-13.
*/
public class 二分查找_非递归 {

public static void main(String[] args) {

int[] a = new int[] {1,2,3,4,5,6,7,8,9,10,11,12,13,14};

}

/**
* 二分查找（非递归）
* @param array
* @param start
* @param end
* @param key
* @return
*/
public static int binSearch(int[] array, int start, int end, int key) {

while(start <= end) {
//计算中间位置
int mid = (start+end)/2;
//判断
if(key == array[mid]) {
return mid;
} else if(key < array[mid]) {
end = mid-1;
} else {
start = mid+1;
}
}
return -1;
}
}