Factorial of a Number

Easy
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196 upvotes
Asked in companies
HCL TechnologiesNagarro SoftwareCapegemini Consulting India Private Limited

Problem statement

Write a program to find the factorial of a number.

Factorial of n is:

n! = n * (n-1) * (n-2) * (n-3)....* 1

Output the factorial of 'n'. If it does not exist, output 'Error'.

Detailed explanation ( Input/output format, Notes, Images )
Input format : 
The only line of input contains a single integer.
Output format : 
The only line of output prints the Factorial of the number or "Error" if it doesn't exist.
Constraints: 
-10 <= n <= 12
Sample Input 1 :
5
Sample Output 1 :
120
Explanation of Sample Input 1:
5!=5*4*3*2*1=120
Sample Input 2 :
0
Sample Output 2 :
1
Explanation of Sample Input 2:
Its a fact that 0!=1
Sample Input 3 :
-2
Sample Output 3 :
Error
Explanation of Sample Input 3:
It's a fact that we can't find the factorial of a negative number.
Approaches (2)
Using while() loop
  • This can be done using an if-else-if ladder to check for negative,0, and positive numbers.
  • If the input is a positive number use a while loop to multiply n with n-1, n-2…1 and get the desired output.
Time Complexity
Space Complexity
Code Solution
(100% EXP penalty)
Factorial of a Number
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