513. Find Bottom Left Tree Value（LeetCode）

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:

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     int findBottomLeftValue(TreeNode* root) {
13         int rlt;
14         queue<TreeNode*> nodes;
15         nodes.push(root);
16         while (!nodes.empty())
17         {
18             int _size = nodes.size();
19             cout<<_size<<endl;
20             rlt = nodes.front()->val;
21            // cout<<rlt<<endl;
22             while (_size)
23             {
24                 TreeNode* tmp = nodes.front();
25                 nodes.pop();
26                 if (tmp->left)
27                 {
28                     nodes.push(tmp->left);
29                 }
30                 if (tmp->right)
31                 {
32                     nodes.push(tmp->right);
33                 }
34                 _size--;
35             }
36 
37         }
38         return rlt;
39     }
40 };