折半查找(递归算法)

#include<stdio.h>
#include<stdlib.h>
int a[1000],k;
int f(int s,int t){
int m;
m=(s+t)/2;
if(a[m]==k)
return m;
else if(k>a[m] && m+1<=t)
return f(m+1,t);
else if(k<a[m] && s<=m-1)
return f(s,m-1);
return -1;
}
int main(){
int i,j,m,n,ans=-1;
scanf("%d%d",&n,&k);
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
printf("%d\n",f(1,n));
return 0;
}