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107.二叉树的层序遍历-ii.cpp
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107.二叉树的层序遍历-ii.cpp
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#include <vector>
#include <algorithm>
#include <stack>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <deque>
#include <list>
#include <string>
using namespace std;
/*
* @lc app=leetcode.cn id=107 lang=cpp
*
* [107] 二叉树的层序遍历 II
*/
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) {}
};
// @lc code=start
/**
* 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>> res;
vector<vector<int>> levelOrderBottom(TreeNode *root)
{
queue<TreeNode*> tq;
if (root) {
tq.push(root);
}
while (!tq.empty()) {
int csize = tq.size();
vector<int> tres;
for (int i = 0; i < csize; ++i) {
TreeNode* node = tq.front();
tq.pop();
tres.push_back(node->val);
if (node->left) {
tq.push(node->left);
}
if (node->right) {
tq.push(node->right);
}
}
res.push_back(tres);
}
reverse(res.begin(), res.end());
return res;
}
};
// @lc code=end