一、

二、

五、二叉樹的垂直遍歷

題目：987. Vertical Order Traversal of a Binary Tree

C++ Soution 1:

 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     vector<vector<int>> verticalTraversal(TreeNode* root) 
13     {
14         map<int, vector<int> > m;  
15         queue<pair<int, TreeNode*> > q; 
16         q.push(make_pair(0, root));  
17         while
 
 (!q.empty())
18         {
19             set<pair<int, int> > tmp; 
20             int len = q.size();
21             for (int i = 0; i < len; ++i)
22             {
23                 auto p = q.front(); q.pop();
24                 tmp.insert(make_pair(p.first, p.second->val));
 
25                 if (p.second->left) q.push(make_pair(p.first - 1, p.second->left));
26                 if (p.second->right) q.push(make_pair(p.first + 1, p.second->right));
27             }
28 
29             for (auto p : tmp) m[p.first].push_back(p.second);
30         }
31 
32         vector<vector<int> > res;
33         for (auto kv : m) res.push_back(kv.second);
34         return res;
35     }
36 };

【Leetcode | 5】二叉樹系列（十三）