【开源社区openEuler实践】 D. Cat, Fox and Maximum Array Split

题目

思路：

#include<bits/stdc++.h>
using namespace std;

#define double long double
#define int long long

int ask(int l, int x){
	cout << '?' << ' ' << l << ' ' << x << '\n';
	cout.flush();
	int res;
	cin >> res;
	return res;
}

void print(int x){
	cout << "! " << x << '\n';
	cout.flush();
	int res;
	cin >> res;
}

void solve(){
	int n, k;
	cin >> n >> k;
	int mx = 0;
	for(int i = 1; i <= n; i++){
		int r = ask(1, n * i);
		if(r == n){
			mx = i;
			break;
		}
	}
	auto check = [&](int val) -> bool {
		int cur = 1;
		for(int i = 1; i <= k; i++){
			if(cur > n) return 0;
			int r = ask(cur, val);
			if(r == n + 1) return 0;
			cur = r + 1;
		}
		return cur == n + 1;
	};
	for(int i = 1; i <= n / k; i++){
		int val = i * mx;
		if(check(val)){
			print(val);
			return;
		}
	}
	print(-1);
}
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout << fixed << setprecision(10);
	int T = 1;
	cin >> T;
	while(T--){
		solve();
	} 
	return 0;
}