Codeforces Round #499 (Div. 2) E. Border
E. Border
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Astronaut Natasha arrived on Mars. She knows that the Martians are very poor aliens. To ensure a better life for the Mars citizens, their emperor decided to take tax from every tourist who visited the planet. Natasha is the inhabitant of Earth, therefore she had to pay the tax to enter the territory of Mars.
There are nn banknote denominations on Mars: the value of ii-th banknote is aiai. Natasha has an infinite number of banknotes of each denomination.
Martians have kk fingers on their hands, so they use a number system with base kk. In addition, the Martians consider the digit dd (in the number system with base kk) divine. Thus, if the last digit in Natasha's tax amount written in the number system with the base kk is dd, the Martians will be happy. Unfortunately, Natasha does not know the Martians' divine digit yet.
Determine for which values dd Natasha can make the Martians happy.
Natasha can use only her banknotes. Martians don't give her change.
Input
The first line contains two integers nn and kk (1≤n≤1000001≤n≤100000, 2≤k≤1000002≤k≤100000) — the number of denominations of banknotes and the base of the number system on Mars.
The second line contains nn integers a1,a2,…,ana1,a2,…,an (1≤ai≤1091≤ai≤109) — denominations of banknotes on Mars.
All numbers are given in decimal notation.
Output
On the first line output the number of values dd for which Natasha can make the Martians happy.
In the second line, output all these values in increasing order.
Print all numbers in decimal notation.
Examples
input
Copy
2 8 12 20
output
Copy
2 0 4
input
Copy
3 10 10 20 30
output
Copy
1 0
Note
Consider the first test case. It uses the octal number system.
If you take one banknote with the value of 1212, you will get 148148 in octal system. The last digit is 4848.
If you take one banknote with the value of 1212 and one banknote with the value of 2020, the total value will be 3232. In the octal system, it is 408408. The last digit is 0808.
If you take two banknotes with the value of 2020, the total value will be 4040, this is 508508 in the octal system. The last digit is 0808.
No other digits other than 0808 and 4848 can be obtained. Digits 0808 and 4848 could also be obtained in other ways.
The second test case uses the decimal number system. The nominals of all banknotes end with zero, so Natasha can give the Martians only the amount whose decimal notation also ends with zero.
題意:有n種類型的紙幣,以十進位制給出,每種紙幣能無限使用,轉換成k進位制數,求有末尾的數有多少種可能。
思路:首先一個數轉換成k進位制數末尾的數為num%k, 由裴蜀定理可知 a1*x1 + a2*x2 +...+ an * xn = c 有整數解,必有gcd(a1, a2,...,an) | c, 所以 最後結果就是 x*gcd % k 0 <= x < k, 的集合
#include <bits/stdc++.h>
using namespace std;
#define N 100
int gcd(int a, int b)
{
if(b == 0)
return a;
return gcd(b, a % b);
}
int main()
{
int n, k;
cin >> n >> k;
int t;
int sum = 0;
for(int i = 1; i <= n; ++i) {
cin >> t;
sum = gcd(sum, t);
}
set<long long>s;
for(int i = 0; i < k; i ++) {
s.insert(((long long)i*sum) % k);
}
printf("%d\n", s.size());
for(auto res : s) {
printf("%lld ", res);
}
return 0;
}
/*
10 4
0 0 1 0
*/