The tree data structure implemented (Tree) and Basic Operation

The definition of the tree

FIG tree is a data structure that is n (n> = 0) consisting of a finite set of nodes having a hierarchical relationship. We call it the "tree" because it looks like an upside down tree, which means that it is the root upward, downward and leaves.

typedef struct BTree	//二叉树
{
	int val;
	struct BTree* rigth;
	struct BTree* left;
}BTree, *BTreePtr;

Creation and destruction of the tree

Recursive algorithm, you can easily create and destroy a tree.

TreeNode* CreateTree()
{
	int input = 0;
	scanf_s("%d", &input);

	TreeNode* t;

	if (input != 0)
	{
		t = (TreeNode*)malloc(sizeof(TreeNode));
		t->val = input;

		printf("\n%d的左孩子:\n", t->val);
		t->left = CreateTree();
		printf("\n%d的有孩子:\n", t->val);
		t->left = CreateTree();
	}
	else
	{
		return NULL;
	}

	return t;
}

void DestroyBTree(BTree* t)
{
	if (!t)
		return;

	BTree* left = t->left;
	BTree* rigth = t->rigth;
	free(t);
	t = NULL;
	DestroyBTree(left);
	DestroyBTree(rigth);
}

Traversing the tree

Preorder (Preorder)

Root -> left child -> right child.

void PreorderTraverseBTree(BTree* tree)
{
	if (!tree)
		return;
	printf("%d\t", tree->val);

	PreorderTraverseBTree(tree->left);
	PreorderTraverseBTree(tree->rigth);
}

Inorder traversal (Inorder)

Left child node -> root -> right child

void inorderBTree(BTree* tree)
{
	//递归出口
	if (!tree)
		return;

	inorderBTree(tree->left);
	printf("%d\t", tree->val);
	inorderBTree(tree->rigth);
}

Postorder (postorder)

Left child node -> right child -> root

void postorderBTree(BTree* tree)
{
	if (!tree)
		return;
	postorderBTree(tree->left);
	postorderBTree(tree->rigth);
	printf("%d\t", tree->val);
}

References Baidu Encyclopedia