Data commit

Task/Tree-traversal/C/tree-traversal.c

@@ -0,0 +1,146 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+typedef struct node_s
+{
+  int value;
+  struct node_s* left;
+  struct node_s* right;
+} *node;
+
+node tree(int v, node l, node r)
+{
+  node n = malloc(sizeof(struct node_s));
+  n->value = v;
+  n->left  = l;
+  n->right = r;
+  return n;
+}
+
+void destroy_tree(node n)
+{
+  if (n->left)
+    destroy_tree(n->left);
+  if (n->right)
+    destroy_tree(n->right);
+  free(n);
+}
+
+void preorder(node n, void (*f)(int))
+{
+  f(n->value);
+  if (n->left)
+    preorder(n->left, f);
+  if (n->right)
+    preorder(n->right, f);
+}
+
+void inorder(node n, void (*f)(int))
+{
+  if (n->left)
+    inorder(n->left, f);
+  f(n->value);
+  if (n->right)
+    inorder(n->right, f);
+}
+
+void postorder(node n, void (*f)(int))
+{
+  if (n->left)
+    postorder(n->left, f);
+  if (n->right)
+    postorder(n->right, f);
+  f(n->value);
+}
+
+/* helper queue for levelorder */
+typedef struct qnode_s
+{
+  struct qnode_s* next;
+  node value;
+} *qnode;
+
+typedef struct { qnode begin, end; } queue;
+
+void enqueue(queue* q, node n)
+{
+  qnode node = malloc(sizeof(struct qnode_s));
+  node->value = n;
+  node->next = 0;
+  if (q->end)
+    q->end->next = node;
+  else
+    q->begin = node;
+  q->end = node;
+}
+
+node dequeue(queue* q)
+{
+  node tmp = q->begin->value;
+  qnode second = q->begin->next;
+  free(q->begin);
+  q->begin = second;
+  if (!q->begin)
+    q->end = 0;
+  return tmp;
+}
+
+int queue_empty(queue* q)
+{
+  return !q->begin;
+}
+
+void levelorder(node n, void(*f)(int))
+{
+  queue nodequeue = {};
+  enqueue(&nodequeue, n);
+  while (!queue_empty(&nodequeue))
+  {
+    node next = dequeue(&nodequeue);
+    f(next->value);
+    if (next->left)
+      enqueue(&nodequeue, next->left);
+    if (next->right)
+      enqueue(&nodequeue, next->right);
+  }
+}
+
+void print(int n)
+{
+  printf("%d ", n);
+}
+
+int main()
+{
+  node n = tree(1,
+                tree(2,
+                     tree(4,
+                          tree(7, 0, 0),
+                          0),
+                     tree(5, 0, 0)),
+                tree(3,
+                     tree(6,
+                          tree(8, 0, 0),
+                          tree(9, 0, 0)),
+                     0));
+
+  printf("preorder:    ");
+  preorder(n, print);
+  printf("\n");
+
+  printf("inorder:     ");
+  inorder(n, print);
+  printf("\n");
+
+  printf("postorder:   ");
+  postorder(n, print);
+  printf("\n");
+
+  printf("level-order: ");
+  levelorder(n, print);
+  printf("\n");
+
+  destroy_tree(n);
+
+  return 0;
+}