Small Factorial

Tried two approach for the problem below:

You are asked to calculate factorials of some small positive integers.

Input
An integer t, 1<=t<=100, denoting the number of testcases, followed by t lines, each containing a single integer n, 1<=n<=100.

Output
For each integer n given at input, display a line with the value of n!

Time limit 2 sec(s)

Memory limit 256 MB

Source limit 1024 KB

(http://www.hackerearth.com/problem/small-factorials/)

/*Without recurrsion*/

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.math.BigInteger;

public class factorial {

    public static void main(String args[] ) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int t = Integer.parseInt(br.readLine());

        int arr[] = new int[t];

        for (int i = 0; i < t; i++) {

            arr[i] = Integer.parseInt(br.readLine());        

        }

        

        for(int i=0; i<t; i++){

            BigInteger res= BigInteger.valueOf(1);

            while(arr[i]>1){

                res = res.multiply(BigInteger.valueOf(arr[i]--));

            }

            System.out.println(res);        

        }        

    }

}

Statistics:

Result

Time (Sec)

Memory (KiB)

100

3.3222

11790732

/*With recurrsion*/

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.math.BigInteger;

public class recurrsion_fact {

    public static void main(String args[] ) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int t = Integer.parseInt(br.readLine());

int arr[] = new int[t];

for (int i = 0; i < t; i++) {

    arr[i] = Integer.parseInt(br.readLine());        

}

for(int i=0; i<t; i++){

    System.out.println(factorial(arr[i]));

}

    }

   

    private static BigInteger  factorial(int num){

BigInteger  res= BigInteger.valueOf(num);

if(num == 0){

    return BigInteger.valueOf(1);

}

else{

    res = res.multiply(factorial(--num));

}         

return res;

    }        

}

Statistics:

Result

Time (Sec)

Memory (KiB)

100

2.4186

12053904

Recurrsion is a trade off between speed and memory useage. :)