implement bst in c

Author: RichardWeiYang

c-cpp/bst.c

@@ -0,0 +1,197 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <time.h>
+
+enum child_dir {
+left_child,
+right_child,
+root,
+};
+
+struct node {
+unsigned long data; 
+struct node *left;
+struct node *right;
+};
+
+struct root {
+struct node *r;
+};
+
+void dump(struct node *node, int level, enum child_dir dir)
+{
+if (!node)
+return;
+
+dump(node->right, level + 1, right_child);
+
+if (dir == left_child)
+printf("%*s\n", level*3, "|");
+
+printf("%*s - %05lu\n", level*3, " ", node->data);
+
+if (dir == right_child)
+printf("%*s\n", level*3, "|");
+
+dump(node->left, level + 1, left_child);
+}
+
+struct node* find(struct root *root, unsigned long data)
+{
+struct node* n = root->r;
+
+while (n) {
+if (n->data == data)
+return n;
+if (data < n->data)
+n = n->left;
+else
+n = n->right;
+}
+
+return NULL;
+}
+
+struct node* new_node(unsigned long data)
+{
+struct node *n;
+
+n = malloc(sizeof(struct node));
+
+n->data = data;
+n->left = n->right = NULL;
+return n;
+}
+
+void insert(struct root *root, struct node *new)
+{
+struct node *parent;
+
+if (!root->r) {
+root->r = new;
+return;
+}
+
+parent = root->r;
+
+while (true) {
+/* Don't support duplicate data */
+if (new->data == parent->data)
+break;
+
+if (new->data < parent->data) {
+if (!parent->left) {
+parent->left = new;
+break;
+}
+parent = parent->left;
+} else {
+if (!parent->right) {
+parent->right = new;
+break;
+}
+parent = parent->right;
+}
+}
+}
+
+struct node* delete(struct root *root, unsigned long data)
+{
+struct node *n = root->r, **p = &root->r;
+struct node *child;
+
+while (n && n->data != data) {
+if (data < n->data) {
+p = &n->left;
+n = n->left;
+} else {
+p = &n->right;
+n = n->right;
+}
+}
+
+if (!n)
+return NULL;
+
+if (n->left && n->right) {
+struct node *rn = n->right, **rp = &n->right;
+
+while (rn->left) {
+rp = &rn->left;
+rn = rn->left;
+}
+
+n->data = rn->data;
+n = rn;
+p = rp;
+}
+
+child = n->left ? n->left : n->right;
+*p = child;
+
+return NULL;
+}
+
+void insert_test()
+{
+struct root tree;
+struct node* n;
+
+tree.r = NULL;
+
+insert(&tree, new_node(9));
+
+insert(&tree, new_node(5));
+insert(&tree, new_node(2));
+insert(&tree, new_node(8));
+
+insert(&tree, new_node(18));
+insert(&tree, new_node(13));
+insert(&tree, new_node(21));
+insert(&tree, new_node(20));
+
+dump(tree.r, 0, root);
+
+n = find(&tree, 18);
+if (n && n->data == 18)
+printf("Get 18\n");
+
+}
+
+void delete_test()
+{
+struct root tree;
+struct node* n;
+
+tree.r = NULL;
+
+insert(&tree, new_node(9));
+
+insert(&tree, new_node(5));
+insert(&tree, new_node(2));
+insert(&tree, new_node(8));
+
+insert(&tree, new_node(18));
+insert(&tree, new_node(13));
+insert(&tree, new_node(21));
+insert(&tree, new_node(20));
+
+dump(tree.r, 0, root);
+
+delete(&tree, 20);
+printf("Delete 20\n");
+dump(tree.r, 0, root);
+
+delete(&tree, 9);
+printf("Delete 9\n");
+dump(tree.r, 0, root);
+}
+
+int main()
+{
+//insert_test();
+delete_test();
+return 0;
+}