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BT_zigzag_traversal.cpp
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BT_zigzag_traversal.cpp
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/**
* 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 {
public:
vector<vector<int>> zigzagLevelOrder(TreeNode* root) {
vector<vector<int>> result;
if(root == NULL)
return result;
queue<TreeNode*> q;
TreeNode* temp = root;
q.push(temp);
int zigzag = 0;
while(!q.empty())
{
vector<int> v;
vector<TreeNode*> arr;
while(!q.empty())
{
arr.push_back(q.front());
q.pop();
}
if(zigzag == 0)
{
for(int i=0; i<arr.size();i++)
{
v.push_back(arr[i]->val);
if(arr[i]->left != NULL){
q.push(arr[i]->left);
}
if(arr[i]->right != NULL){
q.push(arr[i]->right);
}
}
result.push_back(v);
zigzag = 1;
}
else
{
for(int i=0; i<arr.size();i++)
{
if(arr[i]->left != NULL){
q.push(arr[i]->left);
}
if(arr[i]->right != NULL){
q.push(arr[i]->right);
}
}
for(int i=arr.size()-1; i>=0;i--)
{
v.push_back(arr[i]->val);
}
result.push_back(v);
zigzag = 0;
}
}
return result;
}
};