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binary-tree-zigzag-level-order-traversal.cpp
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binary-tree-zigzag-level-order-traversal.cpp
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/**
* Definition for binary tree
* 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) {
// Note: The Solution object is instantiated only once and is reused by each test case.
v.clear(), vv.clear();
int ltr = 1;
stack<TreeNode*> s[2];
if(root != NULL)
s[ltr].push(root);
while(!s[ltr].empty()) {
//ltr ^= 1;
v.clear();
while(!s[ltr].empty()) {
TreeNode *tmp = s[ltr].top();
s[ltr].pop();
Push(s[1^ltr], tmp, ltr);
v.push_back(tmp->val);
}
vv.push_back(v);
ltr ^= 1;
}
return vv;
}
private:
vector<int> v;
vector<vector<int> > vv;
void Push(stack<TreeNode*> &s, TreeNode *node, int ltr) {
if(ltr) {
if(node->left != NULL)
s.push(node->left);
if(node->right != NULL)
s.push(node->right);
} else {
if(node->right != NULL)
s.push(node->right);
if(node->left != NULL)
s.push(node->left);
}
}
};