988. Smallest String Starting From Leaf
Medium
30 Points
String
Backtracking
Tree
Depth-First Search
Binary Tree
You are given the root of a binary tree where each node has a value in the range [0, 25] representing the letters 'a' to 'z'.
Return the lexicographically smallest string that starts at a leaf of this tree and ends at the root.
As a reminder, any shorter prefix of a string is lexicographically smaller.
A leaf of a node is a node that has no children.
Examples
Example 1
Input: root = [0,1,2,3,4,3,4]
Output: "dba"
Example 2
Input: root = [25,1,3,1,3,0,2]
Output: "adz"
Example 3
Input: root = [2,2,1,null,1,0,null,0]
Output: "abc"
Constraints
The number of nodes in the tree is in the range [1, 8500].0 <= Node.val <= 25
988. Smallest String Starting From Leaf
Medium
30 Points
String
Backtracking
Tree
Depth-First Search
Binary Tree
You are given the root of a binary tree where each node has a value in the range [0, 25] representing the letters 'a' to 'z'.
Return the lexicographically smallest string that starts at a leaf of this tree and ends at the root.
As a reminder, any shorter prefix of a string is lexicographically smaller.
A leaf of a node is a node that has no children.
Examples
Example 1
Input: root = [0,1,2,3,4,3,4]
Output: "dba"
Example 2
Input: root = [25,1,3,1,3,0,2]
Output: "adz"
Example 3
Input: root = [2,2,1,null,1,0,null,0]
Output: "abc"
Constraints
The number of nodes in the tree is in the range [1, 8500].0 <= Node.val <= 25