algorithm/Java
1
0
Fork 0
mirror of https://github.com/TheAlgorithms/Java.git synced 2025-12-19 07:00:35 +08:00
Code Issues Packages Projects Releases Wiki Activity

refactor: Enhance docs, code, add tests in KrishnaMurthyNumber (#6742)

Browse Source 
* refactor: Enhance docs, code, add tests in `KrishnaMurthyNumber`

* Lint
This commit is contained in:
Hardik Pawar
2025-10-13 01:34:32 +05:30
committed by GitHub
parent 9a907c8843
commit 74ddea6747
3 changed files with 112 additions and 74 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
src/main/java/com/thealgorithms/maths/KrishnamurthyNumber.java
View File

@@ -3,10 +3,25 @@ package com.thealgorithms.maths;
/**
* Utility class for checking if a number is a Krishnamurthy number.
*
* A Krishnamurthy number (also known as a Strong number) is a number whose sum of the factorials of its digits is equal to the number itself.
* <p>
* A Krishnamurthy number (also known as a Strong number or Factorion) is a
* number
* whose sum of the factorials of its digits is equal to the number itself.
* </p>
*
* For example, 145 is a Krishnamurthy number because 1! + 4! + 5! = 1 + 24 + 120 = 145.
* <p>
* For example, 145 is a Krishnamurthy number because 1! + 4! + 5! = 1 + 24 +
* 120 = 145.
* </p>
*
* <p>
* The only Krishnamurthy numbers in base 10 are: 1, 2, 145, and 40585.
* </p>
*
* <p>
* <b>Example usage:</b>
* </p>
*
* <pre>
* boolean isKrishnamurthy = KrishnamurthyNumber.isKrishnamurthy(145);
* System.out.println(isKrishnamurthy); // Output: true
@@ -14,40 +29,43 @@ package com.thealgorithms.maths;
* isKrishnamurthy = KrishnamurthyNumber.isKrishnamurthy(123);
* System.out.println(isKrishnamurthy); // Output: false
* </pre>
*
* @see <a href="https://en.wikipedia.org/wiki/Factorion">Factorion
* (Wikipedia)</a>
*/
public final class KrishnamurthyNumber {
// Pre-computed factorials for digits 0-9 to improve performance
private static final int[] FACTORIALS = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880};
private KrishnamurthyNumber() {
}
/**
* Checks if a number is a Krishnamurthy number.
*
* @param n The number to check
* <p>
* A number is a Krishnamurthy number if the sum of the factorials of its digits
* equals the number itself.
* </p>
*
* @param n the number to check
* @return true if the number is a Krishnamurthy number, false otherwise
*/
public static boolean isKrishnamurthy(int n) {
int tmp = n;
int s = 0;
if (n <= 0) {
return false;
} else {
while (n != 0) {
// initialising the variable fact that will store the factorials of the digits
int fact = 1;
// computing factorial of each digit
for (int i = 1; i <= n % 10; i++) {
fact = fact * i;
}
// computing the sum of the factorials
s = s + fact;
// discarding the digit for which factorial has been calculated
n = n / 10;
}
// evaluating if sum of the factorials of the digits equals the number itself
return tmp == s;
}
int original = n;
int sum = 0;
while (n != 0) {
int digit = n % 10;
sum = sum + FACTORIALS[digit];
n = n / 10;
}
return sum == original;
}
}