avl trees but with segfaults :(

DSAL/C-Code/avltree.c

+#include <stdio.h>
+#include <stdlib.h>
+#include "avltree.h"
+
+int max(int a, int b) {
+	return (a >= b) ? a : b;
+}
+
+Node* construct_node(int val) {
+	Node* node;
+
+	if ((node = malloc(sizeof(*node))) == NULL) {
+		return NULL;
+	}
+
+	node->data = val;
+	node->left = NULL;
+	node->right = NULL;
+	node->height = 1;
+
+	return node;
+}
+
+Node* rotate_right(Node* node) {
+	Node* new_root;
+	Node* tree2;
+	new_root = node->left;
+	tree2 = new_root->right;
+
+	// rotation
+	new_root->right = node;
+	node->left = tree2;
+
+	// update heights
+	node->height = 1 + max(node->left->height, node->right->height);
+	new_root->height = 1 + max(new_root->left->height, new_root->right->height);
+
+	return new_root;
+}
+
+Node* rotate_left(Node* node) {
+	Node* new_root;
+	Node* tree2;
+	new_root = node->right;
+	tree2 = new_root->left;
+
+	// rotation
+	new_root = node;
+	node->right = tree2;
+
+	// update heights
+	node->height = 1 + max(node->left->height, node->right->height);
+	new_root->height = 1 + max(new_root->left->height, new_root->right->height);
+
+	return new_root;
+}
+
+int get_balance(Node* node) {
+	if (node == NULL) {
+		return 0;
+	}
+	return (node->left->height - node->right->height);
+}
+
+Node* insert(Node* node, int key) {
+	int b;
+
+	// first perform normal BST insert
+	if (node == NULL) {
+		return construct_node(key);
+	}
+
+	if (key < node->data) {
+		node->left = insert(node->left, key);
+	} else if (key > node->data) {
+		node->right = insert(node->right, key);
+	} else {
+		// no duplicates
+		return node;
+	}
+
+	// update height of this node
+	node->height = 1 + max(node->left->height, node->right->height);
+
+	// balancing if necessary
+	b = get_balance(node);
+
+	if (b > 1 && key < node->left->data) {
+		return rotate_right(node);
+	} else if (b < -1 && key > node->right->data) {
+		return rotate_left(node);
+	} else if (b > 1 && key > node->left->data) {
+		node->left = rotate_left(node->left);
+		return rotate_right(node);
+	} else if (b < -1 && key < node->right->data) {
+		node->right = rotate_right(node->right);
+		return rotate_left(node);
+	}	
+
+	return node;
+}
+
+void print_tree(Node* node, int space) {
+	if (node != NULL) {
+		space += 10;
+
+		print_tree(node->right, space);
+
+		printf("\n");
+		for (int i = 10; i < space; i++) {
+			printf(" ");
+		}
+		printf("%d\n", node->data);
+
+		print_tree(node->left, space);
+	}
+}
+
+int main(int argc, char** argv) {
+	Node* root = NULL;
+
+	root = insert(root, 1);
+	print_tree(root, 0);
+	root = insert(root, 2);
+	print_tree(root, 0);
+	root = insert(root, 3);
+	print_tree(root, 0);
+	root = insert(root, 4);
+	print_tree(root, 0);
+	root = insert(root, 5);
+	print_tree(root, 0);
+	root = insert(root, 6);
+	print_tree(root, 0);
+	root = insert(root, 7);
+	print_tree(root, 0);
+	root = insert(root, 8);
+	print_tree(root, 0);
+	return 0;
+}

DSAL/C-Code/avltree.h

+/**
+ * struct node
+ * avl tree node
+ */
+typedef struct Node
+{
+	int data;
+	struct Node* left;
+	struct Node* right;
+	int height;
+} Node;
+
+/**
+ * max function
+ * @param a		first number
+ * @param b		second number
+ * @returns		maximum
+ */
+int max(int, int);
+
+/**
+ * node constructor
+ * @param val	node data
+ * @returns		node
+ */
+Node* construct_node(int);
+
+/**
+ * right rotation
+ * @param node	current root
+ * @returns		new root
+ */
+Node* rotate_right(Node*);
+
+/**
+ * left rotation
+ * @param node	current root
+ * @returns		new root
+ */
+Node* rotate_left(Node*);
+
+/**
+ * get balance value of a node
+ * how much longer is the left subtree compared to the right subtree?
+ * @param node	root node
+ * @returns int	balance value
+ */
+int get_balance(Node*);
+
+/**
+ * insert node to given node
+ * @param node		root node
+ * @param key		node data to be inserted
+ * @returns			new root
+ */
+Node* insert(Node*, int);
+
+/**
+ * print tree
+ * @param node		root node
+ * @param space		how much space to next level
+ */
+void print_tree(Node*, int);