7-1 Prime Day (20 分)

The above picture is from Sina Weibo, showing May 23rd, 2019 as a very cool "Prime Day". That is, not only that the corresponding number of the date 20190523 is a prime, but all its sub-strings ended at the last digit 3 are prime numbers.

Now your job is to tell if a given date is a Prime Day.

Input Specification:

Each input file contains one test case. For each case, a date between January 1st, 0001 and December 31st, 9999 is given, in the format yyyymmdd.

Output Specification:

For each given date, output in the decreasing order of the length of the substrings, each occupies a line. In each line, print the string first, followed by a space, then Yes if it is a prime number, or No if not. If this date is a Prime Day, print in the last line All Prime!.

Sample Input 1:

20190523

 

Sample Output 1:

20190523 Yes
0190523 Yes
190523 Yes
90523 Yes
0523 Yes
523 Yes
23 Yes
3 Yes
All Prime!

 

Sample Input 2:

20191231

 

Sample Output 2:

20191231 Yes
0191231 Yes
191231 Yes
91231 No
1231 Yes
231 No
31 Yes
1 No

#include<bits/stdc++.h>
using namespace std;
const int maxn=1010;
int toInt(string st){
    int sum=0;
    for(int i=0;i<st.size();i++){
        sum=sum*10+(st[i]-'0');
    }
    return sum;
}
bool isP(int n){
    if(n<=1){
        return false;
    }
    for(int i=2;i<=sqrt(n);i++){
        if(n%i==0){
            return false;
        }
    }
    return true;
}

int main(){
    string s,str;
    cin>>s;
    bool flag=true;;
    int len=s.size();
    for(int i=0;i<len;i++){
        str=s.substr(i,len);
        int sum=toInt(str);
        if(isP(sum)){
            printf("%s Yes
",str.c_str());
        }
        else{
            printf("%s No
",str.c_str());
            flag=false;
        }
    }
    if(flag==true){
        printf("All Prime!
");
    }
    return 0;
}