Find Bottom Left Tree Value(LeetCode 513):

Problem

Given the root of a binary tree, return the leftmost value in the last row of the tree.

 

Example 1:

Input: root = [2,1,3]
Output: 1

Example 2:

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

 

Constraints:

  • The number of nodes in the tree is in the range [1, 104].
  • -231 <= Node.val <= 231 - 1