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Copy path107. Binary Tree Level Order Traversal II.cpp
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107. Binary Tree Level Order Traversal II.cpp
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/**
* 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>> levelOrderBottom(TreeNode* root) {
vector<vector <int> > ans;
if( !root)
return ans;
queue <TreeNode*> q;
stack <vector<int>>s ;
q.push(root);
while( ! q.empty())
{
int sz = q.size();
vector<int> x;
for(int i =0; i <sz ; i ++)
{
TreeNode* temp= (q.front());
x.push_back(temp->val);
q.pop();
if( temp->left)
q.push(temp -> left);
if( temp->right)
q.push(temp -> right);
}
s.push(x);
}
while( ! s.empty() )
{
ans.push_back(s.top());
s.pop();
}
return ans;
}
};