题解 | #与7无关的数#

#include<iostream>
#include<string>
using namespace std;

bool judge(int x)
{
    if(x % 7 == 0 ) return true;
    
    string sx = to_string(x);
    for(int i = 0; i < sx.size(); i ++)
    {
        if(sx[i] == '7') return true;
    }
    return false;
}

int solve(int n)
{
    int ans = 0;
    for(int i = 1; i <= n; i++)
    {
        if(!judge(i)) ans += i * i;
    }
    return ans;
}

int main()
{
    int n;
    while(cin >> n)
    {
        cout << solve(n) << endl;
    }
    return 0;
}