1168 Prime Day（20）

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

复习一下string的截取操作str.substr(begin_index,end_index);

以及string to int 操作stoi(str);

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 bool isPrime(int num){
 4     if (num==1)
 5         return false;
 6     if (num==2)
 7         return true;
 8     for(int i=2;i<=num/2;++i){
 9         if (num%i==0)
10             return false;
11     }
12     return true;
13 }
14 int main(){
15     string input;
16     cin>>input;
17     int count=0;
18     for (int i=0;i<input.size();++i){
19         string str_temp=input.substr(i,input.size()); //常用string截取函数
20         int int_temp=stoi(str_temp);  //常用string转数字函数
21         cout<<str_temp<<" ";
22         if (isPrime(int_temp)){
23             cout<<"Yes"<<endl;
24         }
25         else{
26             cout<<"No"<<endl;
27             count++;
28         }
29     }
30     if (count==0){
31         cout<<"All Prime!"<<endl;
32     }
33 }