Last Updated: 9 Dec, 2020
Factorial of a Number
Moderate
Asked in companies
You are given an integer ‘N’. You have to print the value of Factorial of ‘N’. The Factorial of a number ‘N’ is defined as the product of all numbers from 1 to ‘N’.
For Example:
Consider if ‘N’ = 4, the Factorial of 4 will be the product of all numbers from 1 to 4, which is 1 * 2 * 3 * 4 = 24. Hence, the answer is 24.
Input Format:
The first line of the input contains an integer, 'T,’ denoting the number of test cases.
The first and only line of each test case contains one single integer ‘N’ representing the given integer.
Output Format:
For each test case, print the value of factorial of ‘N’.
Print the output of each test case in a separate line.
Constraints:
1 <= T <= 10
1 <= N <= 100
Time limit: 1 sec
Approaches
In this approach, we will calculate the factorial of the given number and store it in the form of a Linked List of digits named digits. To do this, we will define a function multiply(digits,x) that will multiply the number corresponding to the digits with x and update the digits with the product’s value. Then we will initialize the linked list digits with 1 and multiply it with all numbers from 2 to N using the multiply function. At last, we will print the list in reverse order.
Algorithm:
- Defining the Node structure of the linked list:
- The class Node will have two variables, val to store the value and next pointer to store the address of the next element.
- Defining multiply(digits,x) function:
- digits represent the head node of the linked list, and x is the number to be multiplied.
- Declare a variable carry to store carry value and initialize it with 0.
- We will iterate over all the nodes of the digits and update their values.
- Initialize a node temp as digits.
- While temp is not empty, do the following:
- The product prod will the (val of temp * x) + carry.
- Set val of node as prod%10.(Last digit of the prod).
- Update carry as prod/10. (Value after removing the last digit).
- Set temp as next of temp.
- If we still have any carry value left, we have to include some extra digits at the end of the Linked List.
- While carry is not zero, do the following steps:
- Insert a new node with val as carry%10 (last digit of carry) to the end of digits.
- Set carry as carry/10 (The last digit of carry is removed).
- We will declare linked list digits to store the digits of the factorial value.
- Create a node digits with val as 1.
- For each number num from 2 to N, do the following steps:
- Update the values of digits by calling multiply(digits, num).
- Print the linked list digits in reverse order.
In this approach, we will calculate the factorial of the given number and store it in the form of an array of digits named digits. To do this, we will define a function multiply(digits, x) that will multiply the number corresponding to the digits array with x and update the digits array with the product’s value.
We will initialize the digits array with 1 and multiply it with all numbers from 2 to N using the multiply function. At last, we will print the digits array.
Algorithm:
- Defining multiply(digits,x) function:
- Declare a variable carry to store carry value and initialize it with 0.
- We will iterate over all the numbers of the digits array and update its values.
- For each index idx from 0 to length of digits -1, do the following:
- The product prod will the (digits[idx] * x) + carry.
- Set digits[idx] as prod%10.(Last digit of the prod)
- Update carry as prod/10. (Value after removing the last digit)
- If we still have any carry value left, we have to include some extra digits at the end of the digits array.
- While carry is not zero, do the following steps:
- Insert carry%10 (last digit of carry) to the end of digits.
- Set carry as carry/10 (The last digit of carry is deleted).
- We will declare an array digits to store the digits of the factorial value.
- Insert 1 into the array digits.
- For each number num from 2 to N, do the following steps:
- Update the values of digits by calling multiply(digits, num).
- Print the elements of digits array in the reverse order.