improving tree_traversal.c

Author: Gathros

chapters/tree_traversal/code/c/tree_traversal.c

@@ -1,101 +1,59 @@
-#include <stdio.h>
+#include "utility.h"
+
+#include <stddef.h>
 #include <stdlib.h>
-#include <string.h>
+#include <stdio.h>
 
-typedef struct node {
+struct node {
  struct node *children;
- int children_num;
+ size_t children_size;
  int id;
-} node;
-
-typedef struct node_list {
- node n;
- struct node_list *last_list, *next_list;
-} node_list;
-
-typedef struct node_points {
- node_list *start_point, *end_point;
-} node_points;
-
-void push(node_points *np, node n) {
- node_list *temp = (node_list*)malloc(sizeof(node_list));
- temp->n = n;
- temp->last_list = temp->next_list = NULL;
-
- if (!np->end_point) {
- np->start_point = temp;
- } else {
- np->end_point->next_list = temp;
- temp->last_list = np->end_point;
- }
-
- np->end_point = temp;
-}
+};
 
-void stack_pop(node_points *np) {
- node_list *temp;
- temp = np->end_point;
+struct node create_tree(int rows, size_t num_children) {
+ struct node n = {NULL, 0, rows};
 
- if (temp) {
- np->end_point = temp->last_list;
- if (!np->end_point) {
- np->start_point = NULL;
+ if (rows > 0) {
+ n.children = (struct node*)malloc(num_children * sizeof(struct node));
+ n.children_size = num_children;
+ for (size_t i = 0; i < num_children; ++i) {
+ n.children[i] = create_tree(rows - 1, num_children);
  }
-
- free(temp);
  }
-}
-
-void queue_pop(node_points *np) {
- node_list *temp;
- temp = np->start_point;
- if (temp) {
- np->start_point = temp->next_list;
- if (!np->start_point) {
- np->end_point = NULL;
- }
 
- free(temp);
- }
+ return n;
 }
 
-void create_tree(node *n, int num_row, int num_child) {
- n->id = num_row;
- if (num_row == 0) {
- n->children_num = 0;
- return;
- }
+void destroy_tree(struct node n) {
+ if (n.id > 0) {
+ for (size_t i = 0; i < n.children_size; ++i) {
+ destroy_tree(n.children[i]);
+ }
 
- n->children = (node *)malloc(num_child * sizeof(*n->children));
- n->children_num = num_child;
- for (int i = 0; i < num_child; ++i) {
- node child;
- create_tree(&child, num_row - 1, num_child);
- *(n->children + i) = child;
+ free(n.children);
  }
 }
 
-void dfs_recursive(node n) {
+void dfs_recursive(struct node n) {
  printf("%d\n", n.id);
- if (!n.children) {
- return;
- }
 
- for (int i = 0; i < n.children_num; ++i) {
- dfs_recursive(n.children[i]);
+ if (n.children) {
+ for (size_t i = 0; i < n.children_size; ++i) {
+ dfs_recursive(n.children[i]);
+ }
  }
 }
 
-void dfs_recursive_postorder(node n) {
- for (int i = 0; i < n.children_num; ++i) {
+void dfs_recursive_postorder(struct node n) {
+ for (size_t i = 0; i < n.children_size; ++i) {
  dfs_recursive_postorder(n.children[i]);
  }
 
  printf("%d\n", n.id);
 }
 
-void dfs_recursive_inorder_btree(node n) {
- switch (n.children_num) {
+void dfs_recursive_inorder_btree(struct node n) {
+ switch (n.children_size) {
  case 2:
  dfs_recursive_inorder_btree(n.children[0]);
  printf("%d\n", n.id);
@@ -114,65 +72,50 @@ void dfs_recursive_inorder_btree(node n) {
  }
 }
 
-void dfs_stack(node n) {
- node_points stack;
- memset(&stack, 0, sizeof(node_points));
- push(&stack, n);
- node temp;
-
- while (stack.start_point != NULL) {
- temp = stack.end_point->n;
- printf("%d\n", temp.id);
- stack_pop(&stack);
- for (int i = 0; i < temp.children_num; ++i) {
- if (!temp.children) {
- break;
- }
-
- push(&stack, temp.children[i]);
+void dfs_stack(struct node n) {
+ struct stack stk = get_stack(sizeof(struct node*));
+ stack_push(&stk, &n);
+ struct node *tmp;
+
+ while (!stack_empty(&stk)) {
+ tmp = (struct node*)stack_pop(&stk);
+ if (!tmp) {
+ break;
  }
- }
-}
 
-void bfs_queue(node n) {
- node_points queue;
- memset(&queue, 0, sizeof(node_points));
- push(&queue, n);
- node temp;
-
- while (queue.start_point != NULL) {
- temp = queue.start_point->n;
- printf("%d\n", temp.id);
- queue_pop(&queue);
- for (int i = 0; i < temp.children_num; ++i) {
- if (!temp.children) {
- break;
- }
-
- push(&queue, temp.children[i]);
+ printf("%d\n", tmp->id);
+ for (size_t i = 0; i < tmp->children_size; ++i) {
+ stack_push(&stk, &tmp->children[i]);
  }
  }
+
+ free_stack(stk);
 }
 
-void destroy_tree(node *n) {
- if (n->id == 0) {
-  return;
- }
+void bfs_queue(struct node n) {
+ struct queue q = get_queue(sizeof(struct node*));
+ enqueue(&q, &n);
+ struct node *tmp;
 
- for (int i = 0; i < n->children_num; ++i) {
- destroy_tree(n->children + i);
+ while (!queue_empty(&q)) {
+ tmp = (struct node*)dequeue(&q);
+ if (!tmp) {
+ break;
+ }
+
+ printf("%d\n", tmp->id);
+ for (size_t i = 0; i < tmp->children_size; ++i) {
+ enqueue(&q, &tmp->children[i]);
+ }
  }
 
- free(n->children);
+ free_queue(q);
 }
 
 int main() {
- node root;
- create_tree(&root, 3, 3);
- dfs_recursive(root);
- //dfs_stack(root);
- //bfs_queue(root);
- destroy_tree(&root);
+ struct node root = create_tree(3, 3);
+ bfs_queue(root);
+ destroy_tree(root);
 
  return 0;
 }

chapters/tree_traversal/code/c/utility.h

@@ -0,0 +1,105 @@
+#ifndef UTILITY_H
+#define UTILITY_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct stack {
+ void **data;
+ size_t top, capacity, size;
+};
+
+struct queue {
+ void **data;
+ size_t front, back, capacity;
+};
+
+struct stack get_stack(size_t size) {
+ struct stack stk;
+
+ stk.data = malloc(4 * size);
+ stk.capacity = 4;
+ stk.top = 0;
+
+ return stk;
+}
+
+bool stack_empty(struct stack *stk) {
+ return stk->top == 0;
+}
+
+void stack_push(struct stack *stk, void *element) {
+ if (stk->top == stk->capacity) {
+ stk->capacity *= 2;
+ stk->data = realloc(stk->data, stk->capacity * sizeof(stk->data[0]));
+ }
+
+ stk->data[stk->top++] = element;
+}
+
+void *stack_pop(struct stack *stk) {
+ if (stack_empty(stk)) {
+ return NULL;
+ }
+
+ return stk->data[--stk->top];
+}
+
+void free_stack(struct stack stk) {
+ free(stk.data);
+}
+
+struct queue get_queue(size_t size) {
+ struct queue q;
+
+ q.data = calloc(4, size);
+ q.front = 0;
+ q.back = 0;
+ q.capacity = 4;
+
+ return q;
+}
+
+bool queue_empty(struct queue *q) {
+ return q->front == q->back;
+}
+
+void queue_resize(struct queue *q) {
+ size_t size = sizeof(q->data[0]);
+ void **tmp = calloc((q->capacity * 2), size);
+ memcpy(tmp, q->data + q->front, (q->capacity - q->front) * size);
+ memcpy(tmp + q->capacity - q->front, q->data, (q->front - 1) * size);
+
+ q->data = tmp;
+ q->back = q->capacity - 1;
+ q->front = 0;
+ q->capacity *= 2;
+}
+
+void enqueue(struct queue *q, void *element) {
+ if (q->front == (q->back % q->capacity) + 1) {
+ queue_resize(q);
+ }
+
+ q->data[q->back] = element;
+ q->back = (q->back + 1) % q->capacity;
+}
+
+void *dequeue(struct queue *q) {
+ if (queue_empty(q)) {
+ return NULL;
+ }
+
+ void *ret = q->data[q->front];
+ q->front = (q->front + 1) % q->capacity;
+
+ return ret;
+}
+
+void free_queue(struct queue q) {
+ free(q.data);
+}
+
+#endif //UTILITY_H