What's wrong?? -- fctrl2

#include<stdio.h>
int main()
{
int t,n,f=1;
scanf("%d",&t);
int arr[t];
for(int i=1;i<=t;i++)
{
scanf("%d",&arr*);
if(i==t)
break;
}
printf("
“);
for(int j=1;j<=t;j++){
for(int k=1;k<=arr[j];k++)
{
f*=k;
}
printf(”%d
",f );
f=1;
}

}

Let the number whose factorial we need to find be 13. 13! equals 6227020800 which can be written as 6.210^9. You are storing it in an int variable ‘f’ whose maximum value can be equal be to 2,147,483,647 ~ 210^9. Thus you might be getting a wrong answer because of integer overflow condition.

https://discuss.codechef.com/questions/7349/computing-factorials-of-a-huge-number-in-cc-a-tutorial

1 Like

Dear hardy_971 ,

int cannot store factorial of large numbers.

So there are 2 methods of doing it.

1)big integer in c++.This is my accepted code.

https://www.codechef.com/viewsolution/15890382

#include<bits/stdc++.h> // includes every standard library file
#include<boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
using namespace std;
#define ll long long
#include

int main()
{

int t;
cin>>t;
while(t--)
{
    mp::cpp_int n,f=1,i;
    cin>>n;
    
    for(i=1;i<=n;i++)
    f=f*i;
    
    cout << f<<endl;
}

}

2)Another way is by see this link

https://discuss.codechef.com/questions/7349/computing-factorials-of-a-huge-number-in-cc-a-tutorial

i changed the data type to long long, still getting the answer wrong.

Even after using long long there will be an overflow condition for factorial of 23. Here you need to store the answer in a different way like using an array to store the digits of the answer rather than just storing it in a primitive datatype.

1 Like