fix: math/fibonacci linter warnings. (#1047)

* fix: math/fibonacci linter warnings.

* updating DIRECTORY.md

* doxygen

* unit64_t instead of unsigned int
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

math/fibonacci.cpp

@@ -13,12 +13,15 @@
 
 /**
  * Recursively compute sequences
+ * @param n input
+ * @returns n-th element of the Fbinacci's sequence
  */
-unsigned int fibonacci(unsigned int n) {
+uint64_t fibonacci(uint64_t n) {
     /* If the input is 0 or 1 just return the same
        This will set the first 2 values of the sequence */
-    if (n <= 1)
+    if (n <= 1) {
         return n;
+    }
 
     /* Add the last 2 values of the sequence to get next */
     return fibonacci(n - 1) + fibonacci(n - 2);
@@ -30,27 +33,27 @@ unsigned int fibonacci(unsigned int n) {
  * @returns `void`
 */
 static void test() {
-    unsigned int test_case_1 = fibonacci(0);
+    uint64_t test_case_1 = fibonacci(0);
     assert(test_case_1 == 0);
     std::cout << "Passed Test 1!" << std::endl;
 
-    unsigned int test_case_2 = fibonacci(1);
+    uint64_t test_case_2 = fibonacci(1);
     assert(test_case_2 == 1);
     std::cout << "Passed Test 2!" << std::endl;
 
-    unsigned int test_case_3 = fibonacci(2);
+    uint64_t test_case_3 = fibonacci(2);
     assert(test_case_3 == 1);
     std::cout << "Passed Test 3!" << std::endl;
 
-    unsigned int test_case_4 = fibonacci(3);
+    uint64_t test_case_4 = fibonacci(3);
     assert(test_case_4 == 2);
     std::cout << "Passed Test 4!" << std::endl;
 
-    unsigned int test_case_5 = fibonacci(4);
+    uint64_t test_case_5 = fibonacci(4);
     assert(test_case_5 == 3);
     std::cout << "Passed Test 5!" << std::endl;
 
-    unsigned int test_case_6 = fibonacci(15);
+    uint64_t test_case_6 = fibonacci(15);
     assert(test_case_6 == 610);
     std::cout << "Passed Test 6!" << std::endl << std::endl;
 }
@@ -58,7 +61,7 @@ static void test() {
 /// Main function
 int main() {
     test();
-    int n;
+    int n = 0;
     std::cin >> n;
     assert(n >= 0);
     std::cout << "F(" << n << ")= " << fibonacci(n) << std::endl;