Binary Search

Jon Bentley曾经说过类似的话:“90%的程序员无法正确实现二分查找算法

就冲着这句话去写binary search

binary_search 的算法实现部分

/*********************************************************code writer:EOFcode file:binary_search.ccode date:2014.9.18e-mail:[e-mail]:You may have to KNOW that the @array wassequenced from min to max  when you use "binary search".If this function find the element , return thelocation in the @array, otherwise return -1.********************************************************/#include <stdio.h>int binary_search(int* array,int size,int element){if(!array){printf("You passed NULL into function: %s()\n",__FUNCTION__);return -1;}int low = 0;int mid = 0;int high= 0;for(low = 0,high = size-1;low <= high;){mid = (low+high)/2;if(array[mid] < element){low = mid+1;}else if(array[mid] > element){high = mid-1;}else{/*** found that.*/return mid; }}return -1;}

测试用程序

#include <stdio.h>#include "binary_search.h"int main(){int number[10] = {0,2,6,8,10,15,18,40,99};int what_i_want = 18;int ret = 0;ret = binary_search(number,sizeof(number)/sizeof(number[0]),what_i_want);if(ret < 0){printf("Not found!\n");return 0;}printf("location:%d number[%d]:%d\n",ret,ret,number[ret]);return 0;}

update:2015.1.8

添加python版本的实现

'''Code writer : EOFCode date   : 2015.01.08Code file   : bs.pye-mail      : [e-mail] description:       Here is a implementation for how to do binary search in Python.'''def binary_search(array, element):    high = len(array)    mid = -1    for low in range(len(array)) :        mid = (low + high)/2        if array[mid] < element :             low  = mid + 1        elif array[mid] > element :             high = mid - 1        else :             return mid    return -1     def main():    number = [1,2,3,4,5]    print number    print number[binary_search(number,3)]main()