[fix/feat]: remove memory leak in avltree.cpp (#2429)

* fix: remove memory leak by adding deleteAllNodes

* clang-format and clang-tidy fixes for 9d76f8bd

* docs: explain usage of standard headers

* docs: use doxygen syntax

* docs: document parameters of the functions

* style: use proper spelling

* style: simplify logic in deleteNode

* docs: add missing [in]

* docs: add missing slashes

* docs: document `main`

Co-authored-by: David Leal <halfpacho@gmail.com>

* updating DIRECTORY.md

* clang-format and clang-tidy fixes for c852f62d

---------

Co-authored-by: github-actions[bot] <github-actions@users.noreply.github.com>
Co-authored-by: David Leal <halfpacho@gmail.com>

DIRECTORY.md

@@ -19,6 +19,7 @@
   * [Count Of Trailing Ciphers In Factorial N](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/count_of_trailing_ciphers_in_factorial_n.cpp)
   * [Find Non Repeating Number](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/find_non_repeating_number.cpp)
   * [Hamming Distance](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/hamming_distance.cpp)
+  * [Power Of 2](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/power_of_2.cpp)
   * [Set Kth Bit](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/set_kth_bit.cpp)
   * [Travelling Salesman Using Bit Manipulation](https://github.com/TheAlgorithms/C-Plus-Plus/blob/HEAD/bit_manipulation/travelling_salesman_using_bit_manipulation.cpp)
 

bit_manipulation/power_of_2.cpp

@@ -1,11 +1,12 @@
 /**
  * @file
  * @brief [Find whether a given number is power of 2]
- * (https://www.geeksforgeeks.org/program-to-find-whether-a-given-number-is-power-of-2/) implementation
+ * (https://www.geeksforgeeks.org/program-to-find-whether-a-given-number-is-power-of-2/)
+ * implementation
  *
  * @details
- * We are given a positive integer number. We need to check whether the number is power of
+ * We are given a positive integer number. We need to check whether the number
- * 2 or not.
+ * is power of 2 or not.
  *
  * A binary number consists of two digits. They are 0 & 1. Digit 1 is known as
  * set bit in computer terms.
@@ -27,16 +28,16 @@ namespace bit_manipulation {
  * @param n is the number who will be checked
  * @returns either true or false
  */
-bool isPowerOfTwo(
+bool isPowerOfTwo(std ::int64_t n) {  // int64_t is preferred over int so that
-    std ::int64_t n) {  // int64_t is preferred over int so that
+                                      // no Overflow can be there.
-                        // no Overflow can be there.
 
-    return n > 0 && !(n & n - 1); // If we subtract a power of 2 numbers by 1 
+    return n > 0 && !(n & n - 1);  // If we subtract a power of 2 numbers by 1
-    // then all unset bits after the only set bit become set; and the set bit becomes unset.
+    // then all unset bits after the only set bit become set; and the set bit
+    // becomes unset.
 
     // If a number n is a power of 2 then bitwise and of n-1 and n will be zero.
-    // The expression n&(n-1) will not work when n is 0. 
+    // The expression n&(n-1) will not work when n is 0.
-    // To handle this case also, our expression will become n& (!n&(n-1)) 
+    // To handle this case also, our expression will become n& (!n&(n-1))
 }
 }  // namespace bit_manipulation
 

data_structures/avltree.cpp

@@ -6,38 +6,52 @@
  * \warning This program is a poor implementation and does not utilize any of
  * the C++ STL features.
  */
-#include <algorithm>
+#include <algorithm>  /// for std::max
-#include <iostream>
+#include <iostream>   /// for std::cout
-#include <queue>
+#include <queue>      /// for std::queue
 
-typedef struct node {
+using node = struct node {
     int data;
     int height;
     struct node *left;
     struct node *right;
-} node;
+};
 
-/** Create and return a new Node */
+/**
+ * @brief creates and returns a new node
+ * @param[in] data value stored in the node
+ * @return newly created node
+ */
 node *createNode(int data) {
     node *nn = new node();
     nn->data = data;
     nn->height = 0;
-    nn->left = NULL;
+    nn->left = nullptr;
-    nn->right = NULL;
+    nn->right = nullptr;
     return nn;
 }
 
-/** Returns height of tree */
+/**
+ * @param[in] root the root of the tree
+ * @return height of tree
+ */
 int height(node *root) {
-    if (root == NULL)
+    if (root == nullptr) {
         return 0;
+    }
     return 1 + std::max(height(root->left), height(root->right));
 }
 
-/** Returns difference between height of left and right subtree */
+/**
+ * @param[in] root of the tree
+ * @return difference between height of left and right subtree
+ */
 int getBalance(node *root) { return height(root->left) - height(root->right); }
 
-/** Returns Node after Right Rotation */
+/**
+ * @param root of the tree to be rotated
+ * @return node after right rotation
+ */
 node *rightRotate(node *root) {
     node *t = root->left;
     node *u = t->right;
@@ -46,7 +60,10 @@ node *rightRotate(node *root) {
     return t;
 }
 
-/** Returns Node after Left Rotation */
+/**
+ * @param root of the tree to be rotated
+ * @return node after left rotation
+ */
 node *leftRotate(node *root) {
     node *t = root->right;
     node *u = t->left;
@@ -55,55 +72,67 @@ node *leftRotate(node *root) {
     return t;
 }
 
-/** Returns node with minimum value in the tree */
+/**
+ * @param root of the tree
+ * @returns node with minimum value in the tree
+ */
 node *minValue(node *root) {
-    if (root->left == NULL)
+    if (root->left == nullptr) {
         return root;
+    }
     return minValue(root->left);
 }
 
-/** Balanced Insertion */
+/**
+ * @brief inserts a new element into AVL tree
+ * @param root of the tree
+ * @param[in] item the element to be insterted into the tree
+ * @return root of the updated tree
+ */
 node *insert(node *root, int item) {
-    node *nn = createNode(item);
+    if (root == nullptr) {
-    if (root == NULL)
+        return createNode(item);
-        return nn;
+    }
-    if (item < root->data)
+    if (item < root->data) {
         root->left = insert(root->left, item);
-    else
+    } else {
         root->right = insert(root->right, item);
+    }
     int b = getBalance(root);
     if (b > 1) {
-        if (getBalance(root->left) < 0)
+        if (getBalance(root->left) < 0) {
             root->left = leftRotate(root->left);  // Left-Right Case
-        return rightRotate(root);                 // Left-Left Case
+        }
+        return rightRotate(root);  // Left-Left Case
     } else if (b < -1) {
-        if (getBalance(root->right) > 0)
+        if (getBalance(root->right) > 0) {
             root->right = rightRotate(root->right);  // Right-Left Case
-        return leftRotate(root);                     // Right-Right Case
+        }
+        return leftRotate(root);  // Right-Right Case
     }
     return root;
 }
 
-/** Balanced Deletion */
+/**
-node *deleteNode(node *root, int key) {
+ * @brief removes a given element from AVL tree
-    if (root == NULL)
+ * @param root of the tree
+ * @param[in] element the element to be deleted from the tree
+ * @return root of the updated tree
+ */
+node *deleteNode(node *root, int element) {
+    if (root == nullptr) {
         return root;
-    if (key < root->data)
+    }
-        root->left = deleteNode(root->left, key);
+    if (element < root->data) {
-    else if (key > root->data)
+        root->left = deleteNode(root->left, element);
-        root->right = deleteNode(root->right, key);
+    } else if (element > root->data) {
+        root->right = deleteNode(root->right, element);
 
-    else {
+    } else {
         // Node to be deleted is leaf node or have only one Child
-        if (!root->right) {
+        if (!root->right || !root->left) {
-            node *temp = root->left;
+            node *temp = !root->right ? root->left : root->right;
-            delete (root);
+            delete root;
-            root = NULL;
-            return temp;
-        } else if (!root->left) {
-            node *temp = root->right;
-            delete (root);
-            root = NULL;
             return temp;
         }
         // Node to be deleted have both left and right subtrees
@@ -115,7 +144,22 @@ node *deleteNode(node *root, int key) {
     return root;
 }
 
-/** LevelOrder (Breadth First Search) */
+/**
+ * @brief calls delete on every node
+ * @param root of the tree
+ */
+void deleteAllNodes(const node *const root) {
+    if (root) {
+        deleteAllNodes(root->left);
+        deleteAllNodes(root->right);
+        delete root;
+    }
+}
+
+/**
+ * @brief prints given tree in the LevelOrder
+ * @param[in] root of the tree
+ */
 void levelOrder(node *root) {
     std::queue<node *> q;
     q.push(root);
@@ -123,18 +167,23 @@ void levelOrder(node *root) {
         root = q.front();
         std::cout << root->data << " ";
         q.pop();
-        if (root->left)
+        if (root->left) {
             q.push(root->left);
-        if (root->right)
+        }
+        if (root->right) {
             q.push(root->right);
+        }
     }
 }
 
-/** Main function */
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
 int main() {
     // Testing AVL Tree
-    node *root = NULL;
+    node *root = nullptr;
-    int i;
+    int i = 0;
     for (i = 1; i <= 7; i++) root = insert(root, i);
     std::cout << "LevelOrder: ";
     levelOrder(root);
@@ -144,5 +193,6 @@ int main() {
     root = deleteNode(root, 4);  // Deletin key with value 4
     std::cout << "\nLevelOrder: ";
     levelOrder(root);
+    deleteAllNodes(root);
     return 0;
 }