• cf #360 div2 D-Remainders Game(中国剩余定理)


    D. Remainders Game
    time limit per test
    1 second
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Today Pari and Arya are playing a game called Remainders.

    Pari chooses two positive integer x and k, and tells Arya k but not x. Arya have to find the value . There are n ancient numbers c1, c2, ..., cn and Pari has to tell Arya  if Arya wants. Given k and the ancient values, tell us if Arya has a winning strategy independent of value of x or not. Formally, is it true that Arya can understand the value  for any positive integer x?

    Note, that  means the remainder of x after dividing it by y.

    Input

    The first line of the input contains two integers n and k (1 ≤ n,  k ≤ 1 000 000) — the number of ancient integers and value k that is chosen by Pari.

    The second line contains n integers c1, c2, ..., cn (1 ≤ ci ≤ 1 000 000).

    Output

    Print "Yes" (without quotes) if Arya has a winning strategy independent of value of x, or "No" (without quotes) otherwise.

    Examples
    input
    4 5
    2 3 5 12
    
    output
    Yes
    
    input
    2 7
    2 3
    
    output
    No
    
    Note

    In the first sample, Arya can understand  because 5 is one of the ancient numbers.

    In the second sample, Arya can't be sure what  is. For example 1 and 7 have the same remainders after dividing by 2 and 3, but they differ in remainders after dividing by 7.

    题意:给定k和n,给出n个ci,表示你可以知道x%ci。问能否唯一确定x

    思路:首先,根据剩余定理,如果我们想知道x%m等于多少,当且仅当我们知道x%m1,x%m2..x%mr分别等于多少,其中m1m2...mr=m,并且mi相互互质,即构成独立剩余系。令m的素数分解为m=p1^k1p2^k2...pr^kr,如果任意i,都有pi^ki的倍数出现在集合中,那么m就能被猜出来。即k是否存在于素数集合或者存在k的整数倍。

    #include <bits/stdc++.h>
    using namespace std;
    
    long long gcd(long long a,long long b){
        if(b == 0)  return a;
        return gcd(b,a%b);
    }
    long long lcm(long long a,long long b){
        return a*b/gcd(a,b);
    }
    
    int main()
    {
        int n,k;
        while(cin>>n>>k){
            int ans = 1;
            int temp;
            for(int i = 1;i <= n;i ++){
                scanf("%d",&temp);
                ans = gcd(k,lcm(ans,temp));
            }
            if(ans == k)    cout<<"Yes"<<endl;
            else
                cout<<"No"<<endl;
        }
        return 0;
    }
    



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  • 原文地址:https://www.cnblogs.com/Jstyle-continue/p/6351948.html
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