g1001_1100.s1028_recover_a_tree_from_preorder_traversal

Class Solution

java.lang.Object

g1001_1100.s1028_recover_a_tree_from_preorder_traversal.Solution

public class Solution
extends Object

1028 - Recover a Tree From Preorder Traversal.

Hard

We run a preorder depth-first search (DFS) on the root of a binary tree.

At each node in this traversal, we output D dashes (where D is the depth of this node), then we output the value of this node. If the depth of a node is D, the depth of its immediate child is D + 1. The depth of the root node is 0.

If a node has only one child, that child is guaranteed to be the left child.

Given the output traversal of this traversal, recover the tree and return its root.

Example 1:

Input: traversal = “1-2–3–4-5–6–7”

Output: [1,2,5,3,4,6,7]

Example 2:

Input: traversal = “1-2–3—4-5–6—7”

Output: [1,2,5,3,null,6,null,4,null,7]

Example 3:

Input: traversal = “1-401–349—90–88”

Output: [1,401,null,349,88,90]

Constraints:

• The number of nodes in the original tree is in the range [1, 1000].
• 1 <= Node.val <= 109

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
TreeNode	recoverFromPreorder(String traversal)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

recoverFromPreorder

public TreeNode recoverFromPreorder(String traversal)