513. Find Bottom Left Tree Value

题目

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

Example 1:

Input:

    2
   / \
  1   3

Output:
1

Example 2:

Note: You may assume the tree (i.e., the given root node) is not NULL.

给定一个二叉树，在树的最后一行找到最左边的值。注意: 您可以假设树（即给定的根节点）不为 NULL。