二叉树的链式实现-优快云博客

本文链接：https://blog.youkuaiyun.com/paradiso989/article/details/139157673

二叉树的代码实现运用了函数递归的思想，了解函数递归的知识请见：

C语言基础——函数递归-优快云博客

一、二叉树的基础操作

typedef int BTDataType;

typedef struct BinaryTreeNode
{
	BTDataType data; // 当前结点值域	
	struct BinaryTreeNode* left; // 指向当前节点左孩子
	struct BinaryTreeNode* right; // 指向当前节点右孩子
}BTNode;

//创建二叉树
BTNode* CreatBinaryTree();
//前序遍历
void PrevOrder(BTNode* root);
//中序遍历
void InOrder(BTNode* root);
//后序遍历
void PostOrder(BTNode* root);
//结点个数
int	TreeSize(BTNode* root);
//叶子结点个数
int TreeLeafSize(BTNode* root);
//二叉树高度
int TreeHeight(BTNode* root);
//二叉树第k层结点个数
int TreeLevelKSize(BTNode* root, int k);
//二叉树查找值为x的结点
BTNode* TreeFind(BTNode* root, int x);
// 通过前序遍历的数组"ABD##E#H##CF##G##"构建二叉树
BTNode* CreateTree(char* a, int* pi);
//二叉树的销毁
void BinaryTreeDestory(BTNode* root);
// 判断二叉树是否是完全二叉树
bool BinaryTreeComplete(BTNode* root);
//层序遍历
void TreeLevelOrder(BTNode* root);

二、二叉树代码图解

三、二叉树C语言源码汇总

BTNode* BuyNode(int x)
{
	BTNode* node = (BTNode*)malloc(sizeof(BTNode));
	if (node == NULL)
	{
		perror("malloc fail");
		return NULL;
	}

	node->data = x;
	node->left = NULL;
	node->right = NULL;

	return node;
}
//手动造树（测试用）
BTNode* CreatBinaryTree()
{
	BTNode* node1 = BuyNode(1);
	BTNode* node2 = BuyNode(2);
	BTNode* node3 = BuyNode(3);
	BTNode* node4 = BuyNode(4);
	BTNode* node5 = BuyNode(5);
	BTNode* node6 = BuyNode(6);
	BTNode* node7 = BuyNode(7);


	node1->left = node2;
	node1->right = node4;
	node2->left = node3;
	node4->left = node5;
	node4->right = node6;
	node5->right = node7;

	return node1;
}
//前序遍历
void PrevOrder(BTNode* root)
{
	if (root == NULL)
	{
		printf("N ");
		return;
	}
	printf("%d ", root->data);
	PrevOrder(root->left);
	PrevOrder(root->right);
}
//中序遍历
void InOrder(BTNode* root)
{
	if (root == NULL)
	{
		printf("N ");
		return;
	}
	InOrder(root->left);
	printf("%d ", root->data);
	InOrder(root->right);
}
//后序遍历
void PostOrder(BTNode* root)
{
	if (root == NULL)
	{
		printf("N ");
		return;
	}
	PostOrder(root->left);
	PostOrder(root->right);
	printf("%d ", root->data);
}
//结点个数
int TreeSize(BTNode* root)
{
	if (root == NULL)
	{
		return 0;
	}
	return TreeSize(root->left) + TreeSize(root->right) + 1;
}
//叶子结点个数
int TreeLeafSize(BTNode* root)
{
	if (root == NULL)
	{
		return 0;
	}
	if (root->left == NULL && root->right == NULL)
	{
		return 1;
	}

	return TreeLeafSize(root->left) + TreeLeafSize(root->right);

}
//二叉树高度
int TreeHeight(BTNode* root)
{
	if (root == NULL)
	{
		return 0;
	}
	int leftHeight = TreeHeight(root->left);
	int rightHeight = TreeHeight(root->right);

	return leftHeight > rightHeight ?
		leftHeight + 1 : rightHeight + 1;
}
//求第K层的节点数目
int TreeLevelKSize(BTNode* root, int k)
{
	if (root == NULL)
	{
		return 0;
	}
	if (k == 1)
	{
		return 1;
	}
	return TreeLevelKSize(root->left, k - 1) + TreeLevelKSize(root->right, k - 1);
}
//查找值为x的节点
BTNode* TreeFind(BTNode* root, int x)
{
	if (root == NULL)
	{
		return NULL;
	}
	if (root->data == x)
	{
		return root;
	}
	BTNode* ret1 = TreeFind(root->left, x);
	if (ret1)
	{
		return ret1;
	}
	BTNode* ret2 = TreeFind(root->right, x);
	if (ret2)
	{
		return ret2;
	}
	return NULL;
}
// 通过前序遍历的数组"ABD##E#H##CF##G##"构建二叉树
BTNode* CreateTree(char* a, int* pi)
{
	if (a[*pi] == '#')
	{
		(*pi)++;
		return NULL;
	}
	BTNode* root = (BTNode*)malloc(sizeof(BTNode));
	if (root == NULL)
	{
		perror("malloc");
		exit(1);
	}
	root->data = a[(*pi)++];
	root->left = CreateTree(a, pi);
	root->right = CreateTree(a, pi);
	return root;
}
//二叉树的销毁
void BinaryTreeDestory(BTNode* root)
{
	//判空
	if (root == NULL)
	{
		return NULL;
	}
	//释放左子树
	BinaryTreeDestory(root->left);
	//释放右子树
	BinaryTreeDestory(root->right);
	//释放本身结点
	free(root);
}
//层序遍历
void TreeLevelOrder(BTNode* root)
{
	Queue q;
	QueueInit(&q);
	if (root)
	{
		QueuePush(&q, root);
	}
	while (QueueEmpty(&q)==false)
	{
		BTNode* front = QueueFront(&q);
		QueuePop(&q);

		printf("%d ", front->data);

		if (front->left)
		{
			QueuePush(&q, front->left);
		}
		if (front->right)
		{
			QueuePush(&q, front->right);
		}
	}
	QueueDestroy(&q);
}
//判断二叉树是否是完全二叉树
bool BinaryTreeComplete(BTNode* root)
{
	Queue q;
	QueueInit(&q);
	if (root != NULL)
	{
		QueuePush(&q, root);
	}
	//入队遇到空停止入队
	while (!QueueEmpty(&q))
	{
		BTNode* front = QueueFront(&q);
		QueuePop(&q);

		if (front == NULL)
		{
			break;
		}

		QueuePush(&q, front->left);
		QueuePush(&q, front->right);
	}
	//判断后面是否还有非空
	while (!QueueEmpty(&q))
	{
		BTNode* front = QueueFront(&q);
		QueuePop(&q);

		if (front != NULL)
		{
			return false;
		}
	}
	QueueDestroy(&q);
	return true;
}