太久没写了，不知道有没有细节错误，就是输入n个数然后查找某个数查到就输出否则输出-1

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,a[10010],left,mid,right,ask;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	sort(a+1,a+n+1);
	cin>>ask;
	left=1;right=n;
	while(left<right)
	{
		mid=(left+right-1)/2;
		if(ask>a[mid])left=mid+1;
		else right=mid-1;
	}
	if(a[left]==ask) cout<<a[left];
	else cout<<-1;
	return 0;
}