二叉排序树的构造和四种遍历的C实现

#include <stdio.h>
#include<stdlib.h>

//实现排序二叉树的构造，四种遍历
typedef struct node {
	int data;
	node* left;
	node* right;
} Node;

typedef struct {
	Node* root;
} Tree;

void Insert(Tree* t, int value) {
	Node* node = (Node*)malloc(sizeof(Node));
	if (node == NULL)
	{
		return;
	}
	node->data = value;
	node->left = NULL;
	node->right = NULL;

	if (t->root == NULL)
	{
		t->root = node;
	}
	else
	{
		Node* temp = t->root;
		while (temp != NULL)
		{
			if (value < temp->data)
			{
				if (temp->left == NULL)
				{
					temp->left = node;
					return;
				}
				else
				{
					temp = temp->left;
				}
			}
			else
			{
				if (temp->right == NULL)
				{
					temp->right = node;
					return;
				}
				else
				{
					temp = temp->right;
				}
			}
		}
	}

}

void PreOrder(Node* n) {
	if (n != NULL)
	{
		printf("%d ", n->data);
		PreOrder(n->left);
		PreOrder(n->right);
	}
}


void InOrder(Node* n) {
	if (n != NULL)
	{
		InOrder(n->left);
		printf("%d ", n->data);
		InOrder(n->right);
	}

}

void PostOrder(Node* n) {
	if (n != NULL)
	{
		PostOrder(n->left);
		PostOrder(n->right);
		printf("%d ", n->data);
	}
}

//链队列结点定义
typedef struct qnode {
	Node* node;
	qnode* next;
}QNode;

//链队列
typedef struct {
	QNode* front;
	QNode* rear;
}Queue;

//无头结点的链队列初始化
void InitQ(Queue& q) {
	q.front = NULL;
	q.rear = NULL;
}

//入队
void EnQueue(Queue& q, Node* node) {
	QNode* new_node = (QNode*)malloc(sizeof(QNode));
	if (new_node == NULL)
	{
		return;
	}
	new_node->node = node;
	new_node->next = NULL;
	if (q.front==NULL && q.rear==NULL)
	{
		q.front = new_node;
		q.rear = new_node;
	}
	else
	{
		q.rear->next = new_node;
		q.rear = new_node;
	}
}

//出队 注意Node**node这里
void DeQueue(Queue& q, Node* *node) {
	if (q.front == NULL)
	{
		return;
	}
	QNode* denode = q.front;
	*node = denode->node;
    //针对最后一个结点出队这里需要特殊处理 这里卡了一下 开始没有考虑到
	if (denode->next==NULL)
	{
		q.front = NULL;
		q.rear = NULL;
	}
	else
	{
		q.front = denode->next;
	}
	free(denode);
}

void LevelOrder(Node* n) {
	Queue q;
	InitQ(q);
	EnQueue(q, n);
	Node* temp = (Node*)malloc(sizeof(Node));
	while (q.front != NULL)
	{
		DeQueue(q, &temp);
		printf("%d ", temp->data);
		if (temp->left != NULL)
		{
			EnQueue(q, temp->left);
		}
		if (temp->right != NULL)
		{
			EnQueue(q, temp->right);
		}
	}
	printf("\n");
}


int main() {
	Tree t;
	t.root = NULL;
	int arr[8] = { 7,4,8,6,5,3,9,1 };
	for (int i = 0; i < 8; i++)
	{
		Insert(&t, arr[i]);
	}
	printf("\n先序遍历：");
	PreOrder(t.root);
	printf("\n中序遍历：");
	InOrder(t.root);
	printf("\n后序遍历：");
	PostOrder(t.root);
	printf("\n层次遍历：");
	LevelOrder(t.root);
}