exp 8: init

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

7.c

@@ -13,8 +13,6 @@ struct Queue {
   node *tail;
 };
 
-int peek(queue *q) { return q->head->id; }
-
 void insert(queue *q, int id) {
   node *new = malloc(sizeof(node));
   new->id = id;

8.c

@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Node node;
+struct Node {
+  int id;
+  struct Node *left;
+  struct Node *right;
+};
+
+node *new(int id) {
+  node *n = malloc(sizeof(node));
+  n->left = n->right = NULL;
+  n->id = id;
+  return n;
+}
+
+void preorder(node *n) {
+  if (!n)
+    return;
+
+  printf("%d ", n->id);
+  preorder(n->left);
+  preorder(n->right);
+}
+
+void postorder(node *n) {
+  if (!n)
+    return;
+
+  postorder(n->left);
+  postorder(n->right);
+  printf("%d ", n->id);
+}
+
+void inorder(node *n) {
+  if (!n)
+    return;
+
+  inorder(n->left);
+  printf("%d ", n->id);
+  inorder(n->right);
+}
+
+void free_tree(node *n) {
+  if(!n)
+    return;
+
+  free_tree(n->left);
+  free_tree(n->right);
+  free(n);
+}  
+
+int main() {
+  node *root = new(1);
+  root->left = new(4);
+  root->right = new(6);
+  root->left->left = new(2);
+  root->left->right = new(1783);
+  root->left->right->left = new(100);
+
+  printf("Preorder: ");
+  preorder(root);
+  printf("\n");
+  printf("Postorder: ");
+  postorder(root);
+  printf("\n");
+  printf("Inorder: ");
+  inorder(root);
+
+  free_tree(root);
+}