Package g0901_1000.s0988_smallest_string_starting_from_leaf

Class Solution

  • public class Solution
extends Object
    988 - Smallest String Starting From Leaf.

    Medium

    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.

    • For example, "ab" is lexicographically smaller than "aba".

    A leaf of a node is a node that has no children.

    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

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • smallestFromLeaf

        public String smallestFromLeaf​(TreeNode root)