Factorial of a given number

Beginner Problems Basic Maths Easy

You are given an integer n. Return the value of n! or n factorial.

Factorial of a number is the product of all positive integers less than or equal to that number.

Examples:

Input: n = 2

Output: 2

Explanation: 2! = 1 * 2 = 2.

Input: n = 0

Output: 1

Explanation: 0! is defined as 1.

Input: 3

Constraints

0 <= n <= 10

Company Tags

TCS Cognizant Accenture Infosys Capgemini Wipro IBM HCL Tech Mahindra MindTree

Editorial

Intuition:

Given a number, its factorial can be found by multiplying all positive integers starting from 1 to the given number.

Approach:

Initialize a variable with 1 that will store the factorial of the given number.
Start iterating from 1 to the given number, and in every pass multiply the variable with the current number.
After the iterations are completed, the variable storing the answer can be returned.

Dry Run:

Solution:

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

class Solution {
public:

    /* Function to find the
    factorial of a number*/
    int factorial(int n) {
        // Variable to store the factorial
        int fact = 1;

        // Iterate from 1 to n
        for(int i = 1; i <= n; i++) {
            // Multiply fact with current number
            fact = fact * i;
        }
        
        // Return the factorial stored
        return fact;
    }
};

int main()
{
    int n = 4;
    
    /* Creating an instance of 
    Solution class */
    Solution sol; 
    
    // Function call to find the factorial of n
    int ans = sol.factorial(n);
    
    cout << "The factorial of given number is: " << ans;
    
    return 0;
}
class Solution {
    
    /* Function to find the
    factorial of a number */
    public int factorial(int n) {
        // Variable to store the factorial
        int fact = 1;

        // Iterate from 1 to n
        for(int i = 1; i <= n; i++) {
            // Multiply fact with current number
            fact = fact * i;
        }
        
        // Return the factorial stored
        return fact;
    }

    public static void main(String[] args) {
        int n = 4;
        
        /* Creating an instance of 
        Solution class */
        Solution sol = new Solution();
        
        // Function call to find the factorial of n
        int ans = sol.factorial(n);
        
        System.out.println("The factorial of given number is: " + ans);
    }
}
class Solution:
    
    # Function to find the
    # factorial of a number
    def factorial(self, n):
        # Variable to store the factorial
        fact = 1

        # Iterate from 1 to n
        for i in range(1, n + 1):
            # Multiply fact with current number
            fact = fact * i
        
        # Return the factorial stored
        return fact

# Input number
n = 4

# Creating an instance of Solution class
sol = Solution()

# Function call to find the factorial of n
ans = sol.factorial(n)

print("The factorial of given number is: ", ans)
class Solution {
    
    /* Function to find the
    factorial of a number */
    factorial(n) {
        // Variable to store the factorial
        let fact = 1;

        // Iterate from 1 to n
        for (let i = 1; i <= n; i++) {
            // Multiply fact with current number
            fact = fact * i;
        }
        
        // Return the factorial stored
        return fact;
    }
}

// Input number
let n = 4;

// Creating an instance of Solution class
let sol = new Solution();

// Function call to find the factorial of n
let ans = sol.factorial(n);

console.log("The factorial of given number is: ", ans);

Complexity Analysis:

Time Complexity: O(N) – Iterating once from 1 to N.

Space Complexity: O(1) – Using a couple of variables i.e., constant space.

Code

Problem List