LeetCode 剑指 Offer 32 - II. 从上到下打印二叉树 II
解法一(队列):
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
private:
queue<TreeNode*> q;
public:
vector<vector<int>> levelOrder(TreeNode* root) {
vector<vector<int>> rst;
if (root) {
q.push(root);
while (!q.empty()) {
vector<int> temp {};
int curNodeNum = (int)q.size();
for (int i = 0; i < curNodeNum; ++i) {
TreeNode* p = q.front();
q.pop();
temp.emplace_back(p->val);
if (p->left) q.push(p->left);
if (p->right) q.push(p->right);
}
rst.emplace_back(temp);
}
}
return rst;
}
};
解法二: