Resuming work on the repository (#109)

* useless folders removed

* update gitignore

* added comments to missing files

Author: k1ngmang

.gitignore

@@ -1,5 +1,5 @@
 .DS_Store
-.idea/shelf
+/.idea/
 /android.tests.dependencies
 /confluence/target
 /dependencies/repo
@@ -29,4 +29,4 @@ node_modules/
 .rpt2_cache/
 libraries/tools/kotlin-test-nodejs-runner/lib/
 .idea/jarRepositories.xml
-.idea/misc.xml
+.idea/misc.xml

.idea/codeStyles/Project.xml

@@ -1,5 +1,11 @@
 package dynamicProgramming
 
+/**
+ * This is a tail-recursive implementation of factorial calculation.
+ * @param n - the number to calculate factorial for
+ * @param accumulator - accumulates the factorial value (default is 1)
+ * @return factorial of the input number
+ */
 tailrec fun factorial(n: Int, accumulator: Int = 1): Int {
     if (n == 0) {
         return accumulator

.idea/codeStyles/codeStyleConfig.xml

@@ -1,3 +1,8 @@
 package dynamicProgramming
 
-fun Int.isPrime() = this > 1 && (2..(this / 2)).all { this % it != 0 }
+/**
+ * Extension function that checks if an integer is a prime number.
+ * A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.
+ * @return true if the number is prime, false otherwise
+ */
+fun Int.isPrime() = this > 1 && (2..(this / 2)).all { this % it != 0 }