Factorial of a given number

Beginner Problems Basic Maths Easy

Fun Fact: Factorial problems and algorithms are often used in real-world applications for solving problems involving permutations and combinations
This can be found in software related to statistics, probability, data analysis, and also in some optimization algorithms
For instance, Google's search algorithms use factorial calculations for providing various combinations of search results, and in machine learning, factorials play a critical role in calculating the probabilities in Bayesian Networks

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

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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

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