我一直在尝试使用C语言中的队列实现二叉树，我对这种语言还是比较陌生的。我一直在尝试调试我用C编写的代码，从头开始编写代码，但没有结果。我看不出我做错了什么。
我检查了用整数数据写的队列代码，它运行得很好。
然后我实现了二进制搜索树并用
打印了节点中的元素root -> left -> left -> left -> data; //worked fine, was able to reach the extreme left leaf node
和
root -> right -> right -> right -> data; //worked fine, just in case
还有一些像这样的遍历，似乎这棵树形成了很好。我在level_order()函数中打印了队列，我能理解的是队列没有正确构建。不知何故，整个事情进入无限循环。我已经没想完了。这是代码，谢谢。
#include <stdio.h>
#include <stdlib.h>
struct BstNode{
int data;
struct BstNode *left;
struct BstNode *right;
};
struct Queue{
struct BstNode *address;
struct Queue *next;
};
struct Queue *front = NULL;
struct Queue *back = NULL;
struct Queue* create_queue(BstNode **address){
struct Queue *temp = (Queue*)malloc(sizeof(struct Queue));
temp -> next = NULL;
temp -> address = *address;
return temp;
}
void enqueue(BstNode **address){
struct Queue *temp = create_queue(address);
if(front == NULL && back == NULL){
front = back = temp;
}
else{
temp -> next = back;
back = temp;
}
}
void dequeue(){
if(front == NULL){
return;
}
struct Queue* temp;
temp = back;
if(front == back){
front = back = NULL;
}
else{
back = back -> next;
}
free(temp);
}
bool empty(){
if(front == NULL){
return true;
}
return false;
}
void print_queue(){
struct Queue *temp = back;
while(temp != NULL){
printf("%d", temp->address->data);
temp = temp -> next;
}
printf("\n");
}
struct BstNode *root;
struct BstNode *create_node(int data){
struct BstNode *temp = (BstNode *)malloc(sizeof(struct BstNode));
temp -> data = data;
temp -> left = NULL;
temp -> right = NULL;
return temp;
}
void insert_bst_cell(BstNode **node, int data){
if((*node) == NULL){
struct BstNode* temp = create_node(data);
*node = temp;
}
else if(data > (*node)->data){
insert_bst_cell(&(*node)->right, data);
}
else if(data < (*node)->data){
insert_bst_cell(&(*node)->left, data);
}
}
BstNode *first_element(){
return front->address;
}
void level_order(){
if(root == NULL) return;
enqueue(&root);
while(!(empty())){
struct BstNode *current = first_element();
dequeue();
printf("%d\n", current->data);
if(current->right != NULL){
enqueue(&(current->left));
}
if(current->left != NULL){
enqueue(&(current->right));
}
}
}
int main(int argc, char **argv)
{
front = NULL;
back = NULL;
root = NULL;
insert_bst_cell(&root, 15);
insert_bst_cell(&root, 10);
insert_bst_cell(&root, 20);
insert_bst_cell(&root, 5);
insert_bst_cell(&root, 11);
insert_bst_cell(&root, 17);
insert_bst_cell(&root, 25);
insert_bst_cell(&root, 4);
insert_bst_cell(&root, 6);
insert_bst_cell(&root, 9);
insert_bst_cell(&root, 12);
insert_bst_cell(&root, 16);
insert_bst_cell(&root, 19);
insert_bst_cell(&root, 21);
insert_bst_cell(&root, 35);
level_order();
return 0;
}
答案 0 :(得分：1)
感谢Paul Georg Podlech指出我已经实现了堆栈而不是队列。另一个错误是
if(current->right != NULL){
enqueue(&(current->left));
}
if(current->left != NULL){
enqueue(&(current->right));
}
在这个特定的代码中。它应该是
if(current->left != NULL){ //current -> right in previous snippet
enqueue(&(current->left));
}
if(current->right != NULL){ //current -> left in previous snippet
enqueue(&(current->right));
}
以防我发布工作代码
#include <stdio.h>
#include <stdlib.h>
struct BstNode{
int data;
struct BstNode *left;
struct BstNode *right;
};
struct Queue{
struct BstNode *address;
struct Queue *next;
};
struct Queue *front = NULL;
struct Queue *back = NULL;
struct Queue* create_queue(BstNode **address){
struct Queue *temp = (Queue*)malloc(sizeof(struct Queue));
temp -> next = NULL;
temp -> address = *address;
return temp;
}
void enqueue(BstNode **address){
struct Queue *temp = create_queue(address);
if(front == NULL && back == NULL){
front = back = temp;
}
else{
// temp -> next = back;
back -> next = temp;
back = temp;
}
}
void dequeue(){
if(front == NULL){
return;
}
struct Queue* temp;
temp = front;
if(front == back){
front = back = NULL;
}
else{
front = front -> next;
}
free(temp);
}
bool empty(){
if(front == NULL){
return true;
}
return false;
}
void print_queue(){
struct Queue *temp = back;
while(temp != NULL){
printf("%d", temp->address->data);
temp = temp -> next;
}
printf("\n");
}
struct BstNode *root;
struct BstNode *create_node(int data){
struct BstNode *temp = (BstNode *)malloc(sizeof(struct BstNode));
temp -> data = data;
temp -> left = NULL;
temp -> right = NULL;
return temp;
}
void insert_bst_cell(BstNode **node, int data){
if((*node) == NULL){
struct BstNode* temp = create_node(data);
*node = temp;
}
else if(data > (*node)->data){
insert_bst_cell(&(*node)->right, data);
}
else if(data < (*node)->data){
insert_bst_cell(&(*node)->left, data);
}
}
BstNode *first_element(){
return front->address;
}
void level_order(){
if(root == NULL) return;
enqueue(&root);
while(!(empty())){
struct BstNode *current = first_element();
dequeue();
printf("%d\n", current->data);
if(current->left != NULL){
enqueue(&(current->left));
}
if(current->right != NULL){
enqueue(&(current->right));
}
}
}
int main(int argc, char **argv)
{
front = NULL;
back = NULL;
root = NULL;
insert_bst_cell(&root, 15);
insert_bst_cell(&root, 10);
insert_bst_cell(&root, 20);
insert_bst_cell(&root, 5);
insert_bst_cell(&root, 11);
insert_bst_cell(&root, 17);
insert_bst_cell(&root, 25);
insert_bst_cell(&root, 4);
insert_bst_cell(&root, 6);
insert_bst_cell(&root, 9);
insert_bst_cell(&root, 12);
insert_bst_cell(&root, 16);
insert_bst_cell(&root, 19);
insert_bst_cell(&root, 21);
insert_bst_cell(&root, 35);
level_order();
return 0;
}
感谢大家的宝贵时间和投入。