- Graph Theory
- Fan-out, in any tree, is number of pointers to child nodes in a node.
Operation
Preorder Tree Walk （前序遍历）
从根节点开始输出 - 递归到左边 - 递归到右边
输出在两个遍历前
Inorder Tree Walk （中序遍历）
从左到右扫描
从小到大输出
递归到最左边 - 输出 - 递归到右边
输出在两个遍历之间
or use an auxiliary stack Inorder Tree Traversal without Recursion - GeeksforGeeks
void printInorder(struct Node* node)
{
if (node == NULL)
return;
/* first recur on left child */
printInorder(node->left);
/* then print the data of node */
cout << node->data << " ";
/* now recur on right child */
printInorder(node->right);
}Postorder Tree Walk （后序遍历）
从底到上扫描
递归到最下左边 - 输出 - 递归到下右边
Postorder traversal is used to delete the tree. Please see the question for the deletion of a tree for details. Postorder traversal is also useful to get the postfix expression of an expression tree
输出在两个遍历后