#include<stdio.h>
#include<stdlib.h>
int a[]={10,22,42,51,56,63,78,99,102,118};
int binary_search(int low, int high, int key) {
if(low > high)
return -1;
int mid = low + (high - low) / 2;
if(a[mid] == key)
return mid;
return (a[mid] > key ? binary_search(low, mid-1, key) : binary_search(mid+1, high, key));
}
void main() {
int result = binary_search(0, sizeof(a)/sizeof(int), 102);
printf("%d\n",a[result]);
}
注意 int mid = low + (high - low) / 2;这句，很多面试题目都有这个问题，这个主要是编程的细节问题，开始可能想到这样写：int mid = (low + high) / 2;但是 low，和high的值加起来之后有可能超出int的表示范围，从而使其成为负数。
