From daf9c6ba8493bb4000392ef667e3e8238075c341 Mon Sep 17 00:00:00 2001
From: Stoycho Kyosev <68247567+stoychoX@users.noreply.github.com>
Date: Thu, 13 Jan 2022 16:27:15 +0200
Subject: Add pract. 12 solutions

---
 pract_KN/pract. 12/solutions.cpp | 90 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 pract_KN/pract. 12/solutions.cpp

(limited to 'pract_KN/pract. 12/solutions.cpp')

diff --git a/pract_KN/pract. 12/solutions.cpp b/pract_KN/pract. 12/solutions.cpp
new file mode 100644
index 0000000..6615105
--- /dev/null
+++ b/pract_KN/pract. 12/solutions.cpp	
@@ -0,0 +1,90 @@
+#include<iostream>
+
+size_t factRec(size_t number) {
+	if (number == 0)
+		return 1;
+	return number * factRec(number - 1);
+}
+
+size_t powerRec(size_t number, size_t power) {
+	if (power == 0)
+		return 1;
+	return number * powerRec(number, power - 1);
+}
+
+size_t sumOfDigitsRec(size_t number) {
+	if (number == 0)
+		return 0;
+	return number % 10 + sumOfDigitsRec(number / 10);
+}
+
+size_t multRec(size_t firstNumber, size_t secondNumber) {
+	if (secondNumber == 0)
+		return 0;
+	return firstNumber + multRec(firstNumber, secondNumber - 1);
+}
+
+size_t countDigits(size_t number) {
+	if (number < 10)
+		return 1;
+	return 1 + countDigits(number / 10);
+}
+
+size_t flipNumber(size_t number) {
+	if (number < 10)
+		return number;
+	
+	int numberOfDigits = countDigits(number);
+
+	return (number % 10) * powerRec(10, numberOfDigits - 1) + flipNumber(number / 10);
+}
+
+// flipNumber(123)
+// 123 > 10 -> return (123 % 10) * 10 ^ 2 + flipNumber(12)
+
+// flipNumber(12)
+// 12 > 10 -> return (12 % 10) * 10 ^ 1 + flipNumber(1)
+
+// flipNumber(1)
+// 1 < 10 -> return 1;
+
+// flipNumber(1) returned 1 => flipNumber(12) returns (2 * 20 + 1 = 21)
+// flipNumber 12 returned 21 => flipNumber(123) returns (3 * 100 + 21 = 321)
+
+bool primeRec(int number, int border = 2) {
+	if (border * border > number)
+		return true;
+	return number % border && primeRec(number, border + 1);
+}
+
+size_t toBinary(size_t number) {
+	if (number == 0)
+		return number;
+	return number % 2 + 10 * toBinary(number / 2);
+}
+
+// More about binary systems: https://github.com/Angeld55/Introduction_to_programming_FMI/tree/main/Sem.%2007
+
+void printBooleanVectorsRec(int n, int* temp, const int length) {
+	if (n == 0) {
+		for (int i = 0; i < length; i++)
+			std::cout << temp[i];
+		std::cout << std::endl;
+		return;
+	}
+
+	temp[n - 1] = 0;
+	printBooleanVectorsRec(n - 1, temp, length);
+	temp[n - 1] = 1;
+	printBooleanVectorsRec(n - 1, temp, length);
+}
+
+void printBooleanVectors(int n) {
+	int* temp = new int[n];
+	printBooleanVectorsRec(n, temp, n);
+	delete[] temp;
+}
+
+int main() {
+
+}
\ No newline at end of file
-- 
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