LeetCode 103. 二叉树的锯齿形层序遍历

思路

方法：层序遍历

 1 class Solution {
 2 public:
 3     vector<vector<int>> zigzagLevelOrder(TreeNode* root) {
 4         vector<vector<int>> ans;
 5         if (!root) {
 6             return ans;
 7         }
 8 
 9         queue<TreeNode*> nodeQueue;
10         nodeQueue.push(root);
11         bool isOrderLeft = true;
12 
13         while (!nodeQueue.empty()) {
14             deque<int> levelList;
15             int size = nodeQueue.size();
16             for (int i = 0; i < size; ++i) {
17                 auto node = nodeQueue.front();
18                 nodeQueue.pop();
19                 if (isOrderLeft) {
20                     levelList.push_back(node->val);
21                 } else {
22                     levelList.push_front(node->val);
23                 }
24                 if (node->left) {
25                     nodeQueue.push(node->left);
26                 }
27                 if (node->right) {
28                     nodeQueue.push(node->right);
29                 }
30             }
31             ans.emplace_back(vector<int>{levelList.begin(), levelList.end()});
32             isOrderLeft = !isOrderLeft;
33         }
34 
35         return ans;
36     }
37 };

原文：LeetCode官方题解 - 二叉树的锯齿形层序遍历