week10 BST

week10/BST.c

@@ -0,0 +1,103 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * week_10_BST
+ */
+
+#include "BST.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+Node *insertNode(Node **proot, int x) {
+	/* create if empty */
+	if ((*proot) == NULL) {
+		*proot = (Node *)malloc(sizeof(Node));
+		if (*proot == NULL) {
+			fprintf(stderr, "Can not allocate new space for node\n");
+			exit(1);
+		}
+		(*proot)->key = x;
+		(*proot)->left = (*proot)->right = NULL;
+		return *proot;
+	}
+
+	if (x < (*proot)->key) {
+		return insertNode(&((*proot)->left), x);
+	} else if (x > (*proot)->key) {
+		return insertNode(&((*proot)->right), x);
+	}
+
+	/* equal, do nothing and return NULL,
+	 * because insertion is not successful */
+	return NULL;
+}
+
+Node *findNode(Node *root, int x) {
+	/* empty tree */
+	if (root == NULL) {
+		return NULL;
+	}
+
+	if (x < root->key) {
+		return findNode(root->left, x);
+	} else if (x > root->key) {
+		return findNode(root->right, x);
+	}
+
+	/* equal */
+	return root;
+}
+
+Node *deleteNode(Node **proot, int x) {
+	Node *tmpNode;
+
+	/* not found */
+	if (*proot == NULL) {
+		return NULL;
+	}
+
+	/* find the node needs to be delete */
+	if (x < (*proot)->key) {
+		return deleteNode(&((*proot)->left), x);
+	} else if (x > (*proot)->key) {
+		return deleteNode(&((*proot)->right), x);
+	}
+
+	if ((*proot)->left && (*proot)->right) {
+		/* two child, find the min on right to replace */
+		tmpNode = (*proot)->right;
+		while (tmpNode->left) {
+			tmpNode = tmpNode->left;
+		}
+		/* simply replace key value */
+		(*proot)->key = tmpNode->key;
+		/* delete tmpNode, which has one or zero child */
+		return deleteNode(&(*proot)->right, tmpNode->key);
+	} else if ((*proot)->left || (*proot)->right) {
+		/* one child */
+		tmpNode = *proot;
+		if ((*proot)->left) {
+			*proot = (*proot)->left;
+		}
+		if ((*proot)->right) {
+			*proot = (*proot)->right;
+		}
+	} else {
+		/* no child */
+		tmpNode = *proot;
+		*proot = NULL;
+	}
+
+	return tmpNode;
+}
+
+void destroyTree(Node *root) {
+	/* end situation */
+	if (root == NULL) {
+		return;
+	}
+	destroyTree(root->left);
+	destroyTree(root->right);
+	free(root);
+	return;
+}