diff --git a/10_strings/practice/strings_advanced/crossword.cpp b/10_strings/practice/strings_advanced/crossword.cpp
new file mode 100644
index 0000000..fd877dd
--- /dev/null
+++ b/10_strings/practice/strings_advanced/crossword.cpp
@@ -0,0 +1,70 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   crossword.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for advanced_string tasks from practice 10.
+  */
+
+#include <iostream>
+
+const int MAX = 16;
+
+// fill the crossword puzzle with words
+void fill(char cross[][MAX], int size) {
+
+	for (size_t i = 0; i < size - 1 ; i++)
+		std::cin >> cross[i];
+}
+
+void print(char cross[][MAX], int size) {
+
+	for (size_t i = 0; i < size - 1; i++) {
+		for (size_t j = 0; j < size; j++)
+			std::cout << cross[i][j];
+
+		std::cout << '\n';
+	}
+}
+
+// check if given row and column are filled with the same elements
+bool check_word(char cross[][MAX], int size, int row, int col) {
+
+	for (size_t i = 0; i < size -1; i++)
+		if (cross[row][i] != cross[i][col])
+			return false;
+
+	return true;
+}
+
+// check how many rows and columns match
+int check_cross(char cross[][MAX], int size) {
+
+	int result = 0;
+	for (size_t i = 0; i < size - 1; i++) {
+		for (size_t j = 0; j < size - 1; j++)
+			if (check_word(cross, size, i, j))
+				result++;
+	}
+
+	return result;
+}
+
+int main() {
+	
+	char cross[MAX][MAX];
+	int size;
+	std::cin >> size;
+	fill(cross, size);
+
+	std::cout << "\nThe cross looks: \n";
+	print(cross, size);
+	std::cout << "\nYou have: " << check_cross(cross, size) << " matching words! \n";
+
+	return 0;
+}
\ No newline at end of file
diff --git a/10_strings/practice/strings_advanced/dictionary.cpp b/10_strings/practice/strings_advanced/dictionary.cpp
new file mode 100644
index 0000000..4284389
--- /dev/null
+++ b/10_strings/practice/strings_advanced/dictionary.cpp
@@ -0,0 +1,53 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   dictionary.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for advanced_string tasks from practice 10.
+  */
+
+#include <iostream> // cin, cout
+#include <string.h> // strlen, strcat 
+
+const unsigned int WORD_CNT = 3;
+const unsigned int MAX_INPUT = 1024;
+
+bool check_dic(const char* dic[], const char* word) {
+	for (size_t i = 0; i < WORD_CNT; i++)
+		if (strcmp(word, dic[i]) == 0) 	// if the word on position i 
+			return true;				//in the dicionary is as same as the given one
+
+	return false;
+}
+
+int main() {
+
+	const char* dic[] = { "cats", "dogs", "animals" };
+
+	char input[MAX_INPUT];	// "it is raining cats and dogs";
+
+	std::cin.getline(input, MAX_INPUT); //reading the whole input
+
+	//for each word form it, check into the dictionary
+
+	//takes the first word
+	char* curr_word = strtok(input, " ");
+	unsigned int how_many = 0;
+	while (curr_word != nullptr) {
+
+		if (check_dic(dic, curr_word))
+			how_many++;
+
+		// takes the next word form input string
+		curr_word = strtok(nullptr, " "); 
+	}
+
+	std::cout << how_many << '\n';
+
+	return 0;
+}
\ No newline at end of file
diff --git a/10_strings/practice/strings_advanced/sequence.cpp b/10_strings/practice/strings_advanced/sequence.cpp
new file mode 100644
index 0000000..142ba72
--- /dev/null
+++ b/10_strings/practice/strings_advanced/sequence.cpp
@@ -0,0 +1,88 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   sequence.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for advanced_string tasks from practice 10.
+  */
+
+#include <iostream>
+#include <string.h>
+
+size_t get_same_symb_cnt(const char* str) {
+
+	size_t cnt = 1;
+	while (*str != '\0' && *str == *(str + 1)) {
+		++str;
+		++cnt;
+	}
+
+	return cnt;
+}
+
+void resize(char*& str, const char* next_symbols) {
+	
+	if (str == nullptr) {
+		str = new char[strlen(next_symbols) + 1];
+		strcpy(str, next_symbols);
+		return;
+	}
+
+	size_t len = strlen(str);
+	size_t more_symb = strlen(next_symbols);
+	char* new_str = new char[len + more_symb + 1];
+	strcpy(new_str, str);
+	strcat(new_str, next_symbols);
+
+	delete[] str;
+	str = new_str;
+}
+
+char* get_sequence(size_t n) {
+
+	char* result_str = new char[2];
+	strcpy(result_str, "1");
+
+	const char* temp_ptr = result_str;
+	
+	char* temp_str = nullptr;
+
+	char temp[32];
+
+	for (size_t i = 1; i < n; i++) {
+
+		while (*temp_ptr != '\0') {
+
+			size_t symb_cnt = get_same_symb_cnt(temp_ptr);
+
+			temp[0] = '0' + symb_cnt;
+			temp[1] = *temp_ptr;
+			temp[2] = '\0';
+
+			resize(temp_str, temp);
+			temp_ptr += symb_cnt;
+		}
+		delete[] result_str;
+		result_str = new char[strlen(temp_str) + 1];
+		strcpy(result_str, temp_str);
+		delete[] temp_str;
+		temp_str = nullptr;
+		temp_ptr = result_str;
+	}
+
+	delete[] temp_str;
+	return result_str;
+}
+
+int main() {
+
+	char* sequence = get_sequence(5);
+	
+	delete[] sequence;
+	return 0;
+}
diff --git a/10_strings/practice/strings_advanced/yoda_talks.cpp b/10_strings/practice/strings_advanced/yoda_talks.cpp
new file mode 100644
index 0000000..edbc4b3
--- /dev/null
+++ b/10_strings/practice/strings_advanced/yoda_talks.cpp
@@ -0,0 +1,134 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   yoda_talks.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for advanced_string tasks from practice 10.
+  */
+
+#include <iostream>
+#include <string.h> // strtok, strlen, strcpy
+#include <time.h> 	// time
+#include <stdlib.h> // rand
+
+const unsigned int MAX_INPUT = 1024;
+
+// how many spaces are out there + 1
+size_t how_many_words(const char* str) {
+
+	if (str == nullptr)
+		return 0;
+
+	size_t cnt = 1, i = 0; // at least one word
+
+	while (str[i] != '\0') {
+
+		if (str[i] == ' ')
+			cnt++;
+
+		i++;
+	}
+
+	return cnt;
+}
+
+void free_words(char**& words, size_t size) {
+
+	for (size_t i = 0; i < size; i++)
+		delete[] words[i];
+
+	delete words;
+
+	words = nullptr;
+}
+
+void yoda_talks(char** words, size_t size) {
+
+	// here we will check the taken words
+	bool* is_taken_word = new (std::nothrow) bool[size];
+
+	if (is_taken_word == nullptr)
+		return;
+
+	// mark all as untaken
+	for (size_t i = 0; i < size; i++)
+		is_taken_word[i] = false;
+
+	size_t num_taken = 0;
+	size_t index;
+
+	// while there is untaken word
+	while (num_taken < size) {
+
+		index = rand() % size; // trying to take this word
+
+		while (is_taken_word[index])
+			index = (index + 1) % size; // try the next one, if outsize array, start from the beg
+
+		// mark it as taken
+		is_taken_word[index] = true;
+		num_taken++;
+
+		// print it
+		std::cout << words[index];
+
+		if(num_taken != size) // no space after the last word
+			std::cout << ' ';
+	}
+
+	delete[] is_taken_word;
+}
+
+int main() {
+
+	char buff[MAX_INPUT];
+
+	std::cin.getline(buff, MAX_INPUT);
+
+	size_t words_cnt = how_many_words(buff);
+
+	// allocating pointer for each string ( word )
+	char** words = new char*[words_cnt];
+
+	// taking the first word from the buff
+	char* word = strtok(buff, " ");
+
+	int i = 0;
+	while (word != nullptr) {
+
+		// allocating memory for the current word
+		words[i] = new (std::nothrow) char[strlen(word) + 1];
+
+		if (words[i] == nullptr) {
+
+			std::cerr << "can't allocate memory :( !\n";
+			free_words(words, i - 1);
+			return -1;
+		}
+
+		// copying its content
+		strcpy(words[i], word);
+
+		i++;
+
+		// taking the next word
+		word = strtok(nullptr, " ");
+	}
+
+	// makes us sure that all the memory is successfully allocated and copied
+	// for (int j = 0; j < i; j++)
+	// std::cout << words[j] << std::endl;
+
+	srand(time(nullptr));
+
+	yoda_talks(words, words_cnt);
+
+	free_words(words, words_cnt);
+
+	return 0;
+}
\ No newline at end of file
diff --git a/11_recursion/practice/recursion_advanced/task_01_03.cpp b/11_recursion/practice/recursion_advanced/task_01_03.cpp
new file mode 100644
index 0000000..0a8832c
--- /dev/null
+++ b/11_recursion/practice/recursion_advanced/task_01_03.cpp
@@ -0,0 +1,107 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   task_01_03.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for recursion tasks from practice 11.
+  */
+
+#include <iostream>
+
+typedef bool(*fptr)(int); 
+
+const size_t MAXN = 100;
+
+unsigned int addends[MAXN];
+
+void print(size_t len) {
+
+	for (size_t i = 1; i < len; i++)
+		std::cout << addends[i] << '+' ;
+
+	std::cout << addends[len] << '\n';
+}
+
+void create_sum(unsigned int n, size_t pos) {
+
+	if (n == 0) {
+
+		print(pos - 1);
+		return;
+	}
+
+	for (unsigned int k = n; k >= 1; k--) {
+
+		addends[pos] = k;
+
+		if (addends[pos] <= addends[pos - 1])
+			create_sum(n - k, pos + 1);
+	}
+}
+
+void push_back(int*& arr, size_t& size, int elem) {
+	
+	int* result = new int[size + 1];
+	for (size_t i = 0; i < size; i++)
+		result[i] = arr[i];
+
+	result[size] = elem;
+	delete[] arr;
+
+	arr = result;
+	size++;
+}
+
+bool is_even(int number) {
+	return number % 2 == 0;
+}
+
+void print_arr(int* arr, size_t size) {
+
+	for (int i = 0; i < size; ++i)
+		std::cout << arr[i] << ' ';
+	
+	std::cout << std::endl;
+}
+
+void filter_numbers(int*& arr, size_t& size, fptr pred) {
+
+	int* result_arr = nullptr;
+	size_t new_size = 0;
+
+	for (size_t i = 0; i < size; ++i) {
+		if (fptr(arr[i])) {
+			push_back(result_arr, new_size, arr[i]);
+			new_size++;
+		}
+	}
+	delete[] arr;
+	
+	arr = result_arr;
+	size = new_size;
+}
+
+int main() {
+
+	unsigned int n = 7;
+
+	addends[0] = n + 1;
+
+	create_sum(n, 1);
+
+	size_t size = 10;
+	int* arr = new int[size];
+	for(int i = 0; i < size; ++i) {
+		arr[i] = i*i;
+	}
+
+	filter_numbers(arr, size, is_even);
+
+	delete[] arr;
+	return 0;
+}
diff --git a/11_recursion/practice/recursion_advanced/task_05.cpp b/11_recursion/practice/recursion_advanced/task_05.cpp
new file mode 100644
index 0000000..d237a60
--- /dev/null
+++ b/11_recursion/practice/recursion_advanced/task_05.cpp
@@ -0,0 +1,89 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   task_05.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for recursion tasks from practice 11.
+  */
+
+#include <iostream>
+#include <iomanip> // setw
+
+const size_t MAXN = 100;
+const size_t NUM_TESTS = 10;
+
+// the focus it not on dynamic memory, so ..
+unsigned int matrix[MAXN][MAXN] = { 0 };
+
+void print_matrix(size_t k) {
+
+	for (size_t i = 0; i < k; i++) {
+		for (size_t j = 0; j < k; j++)
+			std::cout << std::setw(3)
+				<< matrix[i][j];
+
+		std::cout << std::endl;
+	}
+
+	std::cout << std::endl
+		<< std::endl
+		<< std::endl
+		<< std::endl;
+}
+
+void fill_matrix(const size_t k, size_t it, size_t cur_size) {
+
+	// only one cell to go
+	if (it == k * k) {
+
+		matrix[k / 2][k / 2] = it;
+		return;
+	}
+
+	// begin index
+	size_t start_cell = (k - cur_size) / 2;
+	// end index
+	size_t border = start_cell + cur_size - 1;
+
+	// down fill
+	for (size_t i = 0; i < cur_size; i++)
+		matrix[start_cell + i][start_cell] = it++;
+
+	// right fill ->
+	for (size_t i = 1; i < cur_size; i++)
+		matrix[border][start_cell+ i] = it++;
+
+	// up fill
+	for (size_t i = border - 1; i > start_cell; i--)
+		matrix[i][border] = it++;
+
+	// left fill <-
+	for (size_t i = border; i > start_cell; i--)
+		matrix[start_cell][i] = it++;
+
+	
+	if (it <= k * k)
+		fill_matrix(k, it, cur_size - 2);
+
+}
+
+int main() {
+
+	unsigned int k = 1;
+
+	while (k <= NUM_TESTS) {
+
+		fill_matrix(k, 1, k);
+
+		print_matrix(k);
+
+		k++;
+	}
+
+	return 0;
+}
\ No newline at end of file
diff --git a/11_recursion/practice/recursion_basic/tasks_01-02.cpp b/11_recursion/practice/recursion_basic/tasks_01-02.cpp
index f4f1060..c6c1eb9 100644
--- a/11_recursion/practice/recursion_basic/tasks_01-02.cpp
+++ b/11_recursion/practice/recursion_basic/tasks_01-02.cpp
@@ -1,4 +1,17 @@
-#include <iostream>
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   task_01-02.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for recursion tasks from practice 11.
+  */
+
+#include <iostream>
 
 const int MAX = 12;
 
diff --git a/11_recursion/practice/recursion_basic/tasks_03-04.cpp b/11_recursion/practice/recursion_basic/tasks_03-04.cpp
index af39921..92149ea 100644
--- a/11_recursion/practice/recursion_basic/tasks_03-04.cpp
+++ b/11_recursion/practice/recursion_basic/tasks_03-04.cpp
@@ -1,4 +1,17 @@
-#include <iostream>
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   task_03-04.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for recursion tasks from practice 11.
+  */
+
+#include <iostream>
 
 /*************** Task 3 ***************/
 // print the binary representation of a number
diff --git a/11_recursion/practice/recursion_basic/tasks_05-06.cpp b/11_recursion/practice/recursion_basic/tasks_05-06.cpp
index 0411eaa..8476b62 100644
--- a/11_recursion/practice/recursion_basic/tasks_05-06.cpp
+++ b/11_recursion/practice/recursion_basic/tasks_05-06.cpp
@@ -1,4 +1,17 @@
-#include <iostream>
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   task_05-06.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for recursion tasks from practice 11.
+  */
+
+#include <iostream>
 
 // PAY ATTENTION how swapping two code lines changes the whole program
 /*************** Task 5 ***************/
diff --git a/11_recursion/practice/recursion_basic/tasks_07-08.cpp b/11_recursion/practice/recursion_basic/tasks_07-08.cpp
index c30f357..0159a51 100644
--- a/11_recursion/practice/recursion_basic/tasks_07-08.cpp
+++ b/11_recursion/practice/recursion_basic/tasks_07-08.cpp
@@ -1,3 +1,16 @@
+/****************************************************************************
+ * This file is part of the "Introduction to programming" course. FMI 2019/20
+ *****************************************************************************/
+
+ /**
+  * @file   task_07-08.cpp
+  * @author Ivan Filipov
+  * @author Kristian Krastev
+  * @author Vasilena Peycheva
+  * @date   01.2020
+  * @brief  Solution for recursion tasks from practice 11.
+  */
+
 #include<iostream>
 
 /*************** Task 7 ***************/
diff --git a/practical_tips/debugging_tips/debugger.md b/practical_tips/debugging_tips/debugger.md
new file mode 100644
index 0000000..8d8c7d0
--- /dev/null
+++ b/practical_tips/debugging_tips/debugger.md
@@ -0,0 +1,7 @@
+# Debugging
+
+[Debugging Basics](https://docs.microsoft.com/en-us/visualstudio/debugger/debugging-absolute-beginners?view=vs-2019)
+
+[How to work with the debugger (MSVS)](https://docs.microsoft.com/en-us/visualstudio/debugger/debugger-feature-tour?view=vs-2019&fbclid=IwAR2jRhtIVDZXJzKH2X2LRmmxN1cT73xL74a9PYePzei-808_VigOD5WZuyI)
+
+[![Why debugging is Important](http://i3.ytimg.com/vi/2yXYNxNgJek/maxresdefault.jpg)](https://www.youtube.com/watch?v=2yXYNxNgJek&fbclid=IwAR1kowqfq-HAaClhMP5jRZPf6X3wNFRSI0q_deyblTyLIdh13pL7KftNSZs)