java二分法查找的递归算法如何实现

[fengsheng168]

java二分法查找的递归算法如何实现。。。。。。。。。。。。。

[冰思雨]

楼主举个具体点的例子伐，我都忘了什么是二分法了。

[冰思雨]

package com.houlei.binarySearch;

public class BinarySearch {

	public static void main(String[] args) {
		int [] array = {1,7,9,25,64,98};
		int index = binarySearch(9,array,0,array.length);
		System.out.println("Index : "+index);
	}
	
	public static int binarySearch(int elem,int array [],int low,int high){
		if(low>high)return -1;
		int mid = (low+high)/2;
		if(array[mid] == elem)return mid;
		if(array[mid] < elem) return binarySearch(elem,array,mid+1,high);
		if(array[mid] > elem) return binarySearch(elem, array, low, mid-1);
		return -1;
	}
}

[fengsheng168]

2楼的朋友，在{1,7,7,9,25,64,98} 重值的情况怎么办？？？

[fengsheng168]

在{1,7,7,9,25,64,98}查找7，怎么办？？

[jinjieai4587]

对第二个7做和第一个7相同的操作了，往前就都往前，要么都往后排，折半查找不难写啊。
花点时间想想了。

[LuckilyYu]

这个在百度或google上一搜就有了啊

[samzheng99]

package onlyfortest;

import java.util.Arrays;

public class BinarySearch {
public BinarySearch() {
}
public static void main(String[] args){
int[] iArrays = new int[]{4,7,2,67,23,12,9,0,78,445,67};
Arrays.sort(iArrays);
print(iArrays);
System.out.println("the value is:"+binarySearch(78,iArrays,0,iArrays.length-1));
}
public static int binarySearch(int elem,int[] arrays,int low,int high){
int ret = -1;
if(low>high) return -1;
int mid = (low+high)/2;
System.out.println(mid+" "+arrays[mid]);
if(arrays[mid]==elem){System.out.println("--"+mid); return mid;}
if(arrays[mid]<elem) ret = binarySearch(elem,arrays,mid+1,high);
if(arrays[mid]>elem) ret = binarySearch(elem,arrays,low,mid-1);
System.out.println(mid);
return ret;
}
static void print(int[] arrays){
for(int i=0;i<arrays.length;i++){
System.out.print(" "+arrays[i]);
}
System.out.println();
}
}

[fox_for_cloud]

参考JDK java.util.Arrays的二分法代码不就OK了

[Jalant]

df

[Jalant]

package com.sghlwxf.binarySoft;

public class TestBinarySoft{
public static void main(String args[]){
int[] array= new int[]{9,5,12,43,13,76,4,10,23};
//定义要查找的数
int seek = 76;
//定义下标
int index = 0;
//定义起始位置
int start = 0;
//定义结束位置
int end = 0;
//定义计数器
while(true){
count ++;
// int index = (start + end)/2;
//为了防止start+end溢出,所以写成start+((end - start)/2)
int index = start + ((end - start)/2);
if(array[index]<seek){
start = index;
}else if(array[index]>seek){
end = index;
}else{
break;
}
}
System.out.pritln("所运行的次数是"+count+"地址为"+index);
}
}