题解归档 - cf2225A

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• 本地编号：cf2225A
• 本地来源：problems/cf2225A/idea.md
• 题目链接：https://codeforces.com/contest/2225/problem/A
• 原始标题：cf2225A - A Number Between Two Others

思路

cf2225A - A Number Between Two Others

Let q = y / x.

Any valid z must be k * x with 1 < k < q.
Also y % z != 0 is equivalent to q % k != 0.

• If q = 2, there is no integer k strictly between 1 and q.
• If q >= 3, choose k = q - 1; then q % (q - 1) = 1.

Answer: YES iff y / x >= 3.

代码

来源：problems/cf2225A/solution.cpp

/* Author: likely
 * Time: 2026-06-27
**/
#include<bits/stdc++.h>
#define ll long long
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin>>T;
    while(T--){
        ll x,y;
        cin>>x>>y;
        cout<<((y/x)>=3?"YES":"NO")<<"\n";
    }
    return 0;
}