513. Find Bottom Left Tree Value

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: 

Input:

        1
       / \
      2   3
     /   / \
    4   5   6
       /
      7

Output:
7
题目含义：给定一个二叉树，求最底层的最左边的值

    public int findBottomLeftValue(TreeNode root) {
       Queue<TreeNode> q = new LinkedList<>();
       q.add(root);
       while (!q.isEmpty())
       {
           root = q.poll();
           if (root.right !=null) q.offer(root.right);
           if (root.left !=null) q.offer(root.left);
       }
       return root.val;     
    }