二叉树的锯齿形层序遍历
作者:
Jiarui.X
,
2023-09-19 15:59:17
,
所有人可见
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阅读 28
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
vector<vector<int>> zigzagLevelOrder(TreeNode* root) {
vector<vector<int>> ans;
if(root == nullptr) return ans;
queue<TreeNode*> q;
q.push(root);
bool isOrder = true;
while(q.size()) {
deque<int> dq;
int n = q.size();
for (int i = 0; i < n; i ++) {
auto node = q.front();
q.pop();
if(isOrder) dq.push_back(node->val);
else dq.push_front(node->val);
if(node->left) q.push(node->left);
if(node->right) q.push(node->right);
}
vector<int> res;
for (auto x : dq) res.push_back(x);
ans.push_back(res);
isOrder = !isOrder;
}
return ans;
}
};