题解 | #挑7#

#include <iostream>
using namespace std;


bool IsSeven(int num)
{
     while(num) {
         if (num % 10 == 7) {
             return true;
         }
         num /= 10;
     }
    return false;
}
/*
思路：若num能够整除7，则计数器累加; 若num中含有7的数字，则计数器累加。
*/
int CaculateSevenRelation(int num)
{
    int countSum = 0;
    int temp = 0;
    for(int i = 1; i <= num; i++) {
         if(i % 7 == 0) {
             countSum++;
             continue;
         } else {
            if(IsSeven(i)) {
                countSum++;
            }
         }
       
    }
    return countSum;
    
}
int main()
{
    int num;
    while(cin>>num) {
        cout<<CaculateSevenRelation(num)<<endl;
    }
}