Binary Tree Preorder Traversal
Traverse a binary tree in preorder (root, left, right), iteratively and recursively.
Input format
The first line contains level-order tokens, where N denotes a null node.
Output format
Print the preorder traversal of the tree, space-separated.
Constraints
- Values fit in a 64-bit signed integer
- Trailing whitespace and a trailing newline are ignored by the judge
Read from stdin, write to stdout. Sample cases below show the exact format.
Sample cases
Example 1
Input
51 29 N 17 22 84Expected output
51 29 17 84 22Example 2
Input
82 99 4Expected output
82 99 4