Singles' Day

Singles' Day

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Time Limit: 2 Seconds      Memory Limit: 65536 KB

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Singles' Day(or One's Day), an unofficial holiday in China, is a pop culture entertaining holiday on November 11 for young Chinese to celebrate their bachelor life. With the meaning of single or bachelor of number '1' and the huge population of young single man. This festival is very popular among young Chinese people. And many Young bachelors organize parties and Karaoke to meet new friends or to try their fortunes that day.

On Singles' Day, a supermarket has a promotional activity. Each customer will get a ticket on which there are two integersb and N, representing an integer M that only containsN digits 1 using b as the radix. And if the number M is a prime number, you will get a gift from the supermarket.

Since there are so many customers, the supermarket manager needs your help.

Input

There are multiple test cases. Each line has two integers b and N indicating the integer M, which might be very large. (2 <= b <= 16, 1 <= N <= 16)

Output

If the customer can get a gift, output "YES", otherwise "NO".

暴力求解。。

#include <iostream>#include <cstdio>#include <cmath>using namespace std;bool isPrime[17][17];bool judge (long long m){    if (m == 1) return false;    const long long sm = sqrt(m);    for (int i = 2; i <= sm; ++i)    {        if (m % i == 0)        {            return false;        }    }    return true;}long long convertToDecimal(int b, int n){    long long v = 0;    while (n--)    {        v = v * b + 1;    }    return v;}int main(){    int b, n;    for (b = 2; b < 17; ++b)    {        for (n = 1; n < 17; ++n)        {            long long v = convertToDecimal(b, n);            isPrime[b][n] = judge(v);        }    }    while (scanf("%d %d", &b, &n) != EOF)    {        if (isPrime[b][n])        {            puts("YES");        }        else        {            puts("NO");        }    }    return 0;}