代码应打印AVL树（平衡二叉树）。为什么我的代码不起作用？以下是this website和我的代码。区别仅在于节点的定义。
正确版本：
struct Node
{
int key;
struct Node *left;
struct Node *right;
int height;
};
struct Node* newNode(int key)
{
struct Node* node = (struct Node*)
malloc(sizeof(struct Node));
node->key = key;
node->left = NULL;
node->right = NULL;
node->height = 1; // new node is initially added at leaf
return(node);
}
我（不正确的）现代编译器优化中的代码修改版本：
typedef struct tree *T_tree;
struct tree {
T_tree left;
int key;
T_tree right;
int height;
//int size = 0;
};
T_tree Tree (T_tree l, int k, T_tree r) {
T_tree t = malloc(sizeof(*t));
t-> left=l;
t-> key=k;
t->right = r;
if (l==NULL && r == NULL) {
t->height = 1;
}
/*
else {
t->height++;
}*/
return t;
}
使用main的完整正确代码：
#include<stdio.h>
#include<stdlib.h>
// An AVL tree node
struct Node
{
int key;
struct Node *left;
struct Node *right;
int height;
};
// A utility function to get maximum of two integers
int max(int a, int b);
// A utility function to get the height of the tree
int height(struct Node *N)
{
if (N == NULL)
return 0;
return N->height;
}
// A utility function to get maximum of two integers
int max(int a, int b)
{
return (a > b)? a : b;
}
/* Helper function that allocates a new node with the given key and
NULL left and right pointers. */
struct Node* newNode(int key)
{
struct Node* node = (struct Node*)
malloc(sizeof(struct Node));
node->key = key;
node->left = NULL;
node->right = NULL;
node->height = 1; // new node is initially added at leaf
return(node);
}
// A utility function to right rotate subtree rooted with y
// See the diagram given above.
struct Node *rightRotate(struct Node *y)
{
struct Node *x = y->left;
struct Node *T2 = x->right;
// Perform rotation
x->right = y;
y->left = T2;
// Update heights
y->height = max(height(y->left), height(y->right))+1;
x->height = max(height(x->left), height(x->right))+1;
// Return new root
return x;
}
// A utility function to left rotate subtree rooted with x
// See the diagram given above.
struct Node *leftRotate(struct Node *x)
{
struct Node *y = x->right;
struct Node *T2 = y->left;
// Perform rotation
y->left = x;
x->right = T2;
// Update heights
x->height = max(height(x->left), height(x->right))+1;
y->height = max(height(y->left), height(y->right))+1;
// Return new root
return y;
}
// Get Balance factor of node N
int getBalance(struct Node *N)
{
if (N == NULL)
return 0;
return height(N->left) - height(N->right);
}
// Recursive function to insert a key in the subtree rooted
// with node and returns the new root of the subtree.
struct Node* insert(struct Node* node, int key)
{
/* 1. Perform the normal BST insertion */
if (node == NULL)
return(newNode(key));
if (key < node->key)
node->left = insert(node->left, key);
else if (key > node->key)
node->right = insert(node->right, key);
else // Equal keys are not allowed in BST
return node;
/* 2. Update height of this ancestor node */
node->height = 1 + max(height(node->left),
height(node->right));
/* 3. Get the balance factor of this ancestor
node to check whether this node became
unbalanced */
int balance = getBalance(node);
// If this node becomes unbalanced, then
// there are 4 cases
// Left Left Case
if (balance > 1 && key < node->left->key)
return rightRotate(node);
// Right Right Case
if (balance < -1 && key > node->right->key)
return leftRotate(node);
// Left Right Case
if (balance > 1 && key > node->left->key)
{
node->left = leftRotate(node->left);
return rightRotate(node);
}
// Right Left Case
if (balance < -1 && key < node->right->key)
{
node->right = rightRotate(node->right);
return leftRotate(node);
}
/* return the (unchanged) node pointer */
return node;
}
// A utility function to print preorder traversal
// of the tree.
// The function also prints height of every node
void preOrder(struct Node *root)
{
if(root != NULL)
{
printf("%d ", root->key);
preOrder(root->left);
preOrder(root->right);
}
}
/* Drier program to test above function*/
int main()
{
struct Node *root = NULL;
/* Constructing tree given in the above figure */
root = insert(root, 10);
root = insert(root, 20);
root = insert(root, 30);
root = insert(root, 40);
root = insert(root, 50);
root = insert(root, 25);
/* The constructed AVL Tree would be
30
/ \
20 40
/ \ \
10 25 50
*/
printf("Preorder traversal of the constructed AVL"
" tree is \n");
preOrder(root);
return 0;
}
但这给出了错误的值吗？完整的错误代码，带有main：
#include <stdio.h>
#include <stdlib.h>
typedef struct tree *T_tree;
struct tree {
T_tree left;
int key;
T_tree right;
int height;
//int size = 0;
};
T_tree Tree (T_tree l, int k, T_tree r) {
T_tree t = malloc(sizeof(*t));
t-> left=l;
t-> key=k;
t->right = r;
if (l==NULL && r == NULL) {
t->height = 1;
}
/*
else {
t->height++;
}*/
return t;
}
//bigger of 2 integers:
int max(int a, int b) {
if (a>=b) {
return a;
}
else {
return b;
}
}
//actual height of tree
int height(T_tree t) {
if (t==NULL)
return 0;
return t->height;
}
T_tree rightRotate(T_tree t) {
T_tree t1 = t->left;
T_tree t2 = t1->right;
//rotation:
t1->right = t;
t->left = t2;
//update heights:
t->height = max(height(t->left), height(t->right))+1;
t1->height = max(height(t1->left), height(t1->right))+1;
return t1;
};
T_tree leftRotate(T_tree t) {
T_tree t1 = t->right;
T_tree t2 = t1->left;
//rotation:
t1->left = t;
t->right = t2;
//update heights:
t->height = max(height(t->left), height(t->right))+1;
t1->height = max(height(t1->left), height(t1->right))+1;
return t1;
};
//get balance factor of node N
int getBalance(T_tree node) {
if (node == NULL)
return 0;
return height(node->left) - height(node->right);
}
T_tree insert(int key, T_tree t) {
if (t==NULL) {
return Tree(NULL, key, NULL);
}
if (key < (t->key)) {
Tree(insert(key,t->left), t->key, t->right);
}
else if (key > t->key) {
return Tree(t->left, t->key, insert(key, t-> right));
}
else return Tree(t->left, key, t-> right);
//update height of this node
t->height = 1 + max(height(t->left), height(t->right));
//is node becomed unbalanced?
int balance = getBalance(t);
if (balance >1 && key< t->left->key)
return rightRotate(t);
if (balance <-1 && key > t->right->key)
return leftRotate(t);
if (balance>1 && key > t->left->key) {
t->left = leftRotate(t->left);
return rightRotate(t);
}
if (balance < -1 && key < t->right->key) {
t->right = rightRotate(t->right);
return leftRotate(t);
}
return t;
}
void preOrder(T_tree root)
{
if(root != NULL)
{
printf("%d ", root->key);
preOrder(root->left);
preOrder(root->right);
}
}
int main(int argc, char const *argv[])
{
T_tree t1 = NULL;
t1 = insert(10, t1);
t1 = insert(20, t1);
t1 = insert(30, t1);
t1 = insert(40, t1);
t1 = insert(50, t1);
t1 = insert(15, t1);
preOrder(t1);
return 0;
}
网站上的第一个版本为我提供了正确的值：
30 20 10 25 40 50
但是第二个，如果我在主函数的末尾加15，即使它是相同的打印函数，打印也会忽略它：
10 20 30 40 50
（还有另一个问题：为什么我需要cltr + ka来使代码可见，为什么？也许我应该在我使用的编辑器中设置4个空格宽的标签，这就是为什么粘贴无法完全按照应该吗？）