Please help me with FCTRL2

#1

what is wrong in these solution

#include <iostream>
#include<bits/stdc++.h>
using namespace std;

int main(){
    long long int T, N, i, fact;
    cin >> T;
    while(T--){
        fact = 1;
        cin >> N;
        for(i = 1; i <= N; i++){
            fact = fact * i;
        }
        cout << fact << endl;
    }
}
#2

Seeing the constraints on the value of n,
n=100 is the worst case. Factorial of 100 is 9.332622e+157 which won’t fit in long long range. The fact variable will overflow yielding wrong results.

1 Like
#3

Then what should i have to do?

#4

you can use these library…

#include <boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;

make the data type as cpp_int T,n,i,fact;

1 Like
#5

You can also refer to this

#include <bits/stdc++.h>
using namespace std;

void multiply(int x,vector<int>&mult){
    int carry=0;
    for(auto it=mult.begin();it!=mult.end();it++){
        int temp_product=(*it)*x+carry;
        *it=temp_product%10;
        carry=temp_product/10;
    }
    while(carry){
        mult.push_back(carry%10);
        carry/=10;
    }
}

void factorial(int n){
    vector<int>result;
    result.push_back(1);
    for(int i=2;i<=n;i++)
        multiply(i,result);
    for(auto it=result.rbegin();it!=result.rend();it++)
        cout<<*it;
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int t;
	cin>>t;
	while(t--){
	    int n;
	    cin>>n;
	    factorial(n);
	    cout<<"\n";
	}
	return 0;
}
#6

Boost library is not accepted on many sites. So, I would recommend you for string multiplication