Package 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 java.lang.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
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    TreeNode
    recoverFromPreorder(java.lang.String traversal)
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • recoverFromPreorder

      public TreeNode recoverFromPreorder(java.lang.String traversal)