https://www.codechef.com/problems/LUCKY5

,
1

It is showing wrong answer
#include
using namespace std;

int main(){
int t;
cin>>t;

while(t--){
    int count=0;
    int n;
    cin>>n;
    
    
    while(n){
        int last=n%10;
        if(last!=4&&last!=7){
            count++;
        }
        n=n/10;
    }
    cout<<count<<"\n";
}
return 0;

}

2

The answer is simply the number of unlucky digits. Your logic seems to be wrong.
AC code:

#include <bits/stdc++.h>

using namespace std;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin >> t;
    while (t--)
    {
        string s;
        cin >> s;
        int ans = 0;
        for (char i : s) if (i != '4' && i != '7') ++ans;
        cout << ans << '\n';
    }
}

Also, notice that n can be as large as 10^{100000} which won’t even fit in long long. That’s why you should use a string.

1 Like
3

my logic is right…
as you told…
n value is large…
that’s why we should use string…

thanks bhaiya…