70过不了，三个TLE，清缓存的函数也写了，不清楚问题在哪

#include<iostream>
#include<cmath>
using namespace std;
int num=1000000000;
int leftt,rightt,mid; 
int answer;
int t=2;
int main(){		
	mid=num/t;
	while(true){
		printf("%d\n",mid);
		fflush(stdout)
		scanf("%d",&answer);
		if(answer==0){
			break;
		}
		if(answer==1){
			rightt=mid;
			mid=(rightt+leftt)/t;
		}
		if(answer==-1){
			leftt=mid;
			mid=(rightt+leftt)/t;
		}
	}
	return 0;
}