small changes and some comments

I puted few comments and changed a little bit.

data_structures/binary_trees/binary_search_tree.c

@@ -7,17 +7,27 @@
  - Search by key value
  - Listing of node keys in order of value (from left to right)
 */
- 
+
 // Node, the basic data structure in the tree
 typedef struct node{
+
+    // left child
 	struct node* left;
+
+	// right child
 	struct node* right;
+
+	// data of the node
 	int data;
 } node;
 
 // The node constructor, which receives the key value input and returns a node pointer
 node* newNode(int data){
+
+    // creates a slug
 	node* tmp = (node*)malloc(sizeof(node));
+
+	// initializes the slug
 	tmp->data = data;
 	tmp->left = NULL;
 	tmp->right = NULL;
@@ -52,7 +62,7 @@ node* getMax(node* root){
 // Deletion procedure, which searches for the input key in the tree and removes it if present
 node* delete(node* root, int data){
 	// If the root is null, nothing to be done
-	if (root == NULL) 
+	if (root == NULL)
 		return root;
 	// If the input key is greater than the root's, search in the right subtree
 	else if (data > root->data)
@@ -61,6 +71,7 @@ node* delete(node* root, int data){
 	else if (data < root->data)
 		root->left = delete(root->left, data);
 	// If the input key matches the root's, check the following cases
+	// termination condition
 	else if (data == root->data){
 		// Case 1: the root has no leaves, remove the node
 		if ((root->left == NULL) && (root->right == NULL)){
@@ -82,7 +93,11 @@ node* delete(node* root, int data){
 		}
 		// Case 3: the root has 2 leaves, find the greatest key in the left subtree and switch with the root's
 		else {
+
+            // finds the biggest node in the left branch.
 			node* tmp = getMax(root->left);
+
+			// sets the data of this node equal to the data of the biggest node (lefts)
 			root->data = tmp->data;
 			root->left = delete(root->left, tmp->data);
 		}
@@ -115,7 +130,7 @@ int height(node* root){
 		// Get the height from both left and right subtrees to check which is the greatest
 		int right_h = height(root->right);
 		int left_h = height(root->left);
-		
+
 		// The final height is the height of the greatest subtree(left or right) plus 1(which is the root's level)
 		if (right_h > left_h)
 			return (right_h + 1);
@@ -145,14 +160,19 @@ void inOrder(node* root){
 }
 
 void main(){
-	node* root = NULL;
-	int opt = 1;
-	int data;
 
+    // this reference don't change.
+    // only the tree changes.
+	node* root = NULL;
+	int opt = -1;
+	int data = 0;
+
+    // event-loop.
 	while (opt != 0){
 		printf("\n\n[1] Insert Node\n[2] Delete Node\n[3] Find a Node\n[4] Get current Height\n[5] Print Tree in Crescent Order\n[0] Quit\n");
-		scanf("%d",&opt);
+		scanf("%d",&opt); // reads the choice of the user
 
+        // processes the choice
 		switch(opt){
 			case 1:	printf("Enter the new node's value:\n");
 				scanf("%d",&data);
@@ -164,7 +184,7 @@ void main(){
 					scanf("%d",&data);
 					root = delete(root,data);
 				}
-				else 
+				else
 					printf("Tree is already empty!\n");
 				break;
 
@@ -172,7 +192,7 @@ void main(){
 				scanf("%d",&data);
 				find(root,data) ? printf("The value is in the tree.\n") : printf("The value is not in the tree.\n");
 				break;
-				
+
 			case 4: printf("Current height of the tree is: %d\n", height(root));
 				break;
 
@@ -181,5 +201,6 @@ void main(){
 		}
 	}
 
+    // deletes the tree from the heap.
 	purge(root);
 }