1015. Reversible Primes (20)

题目：https://www.patest.cn/contests/pat-a-practise/1015

注意：0和1都不是素数

#include<cstdio>#include<algorithm>using namespace std;#define MAX   100010bool prime[MAX] = {0};void init(){prime[0] = 1;prime[1] = 1;for(int i=2; i<MAX; i++)for(int j = i*2; j<MAX; j+=i)prime[j] = 1;}int change(int num,int radix){int a[100]={0},len=0,x=0;while (num!=0){a[len] = num%radix;num = num/radix;len++;}for(int i=0; i<len; i++){x = x*radix + a[i];}return x;}int main(){//初始化素数表init();//输入数据while (1){int num,radix,x;scanf("%d",&num);if(num<0)break;scanf("%d",&radix);x = change(num,radix);if(prime[num] == 0 && prime[x] == 0){printf("Yes\n");}else{printf("No\n");}}return 0;}