[LeetCode] Binary Tree Zigzag Level Order Traversal
2017-09-10 20:40
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[Problem]
Given a binary tree, return the zigzag level order
traversal of its nodes' values. (ie, from left to right, then right
to left for the next level and alternate between).
For example:
Given binary tree
return its zigzag level order traversal as:
[Solution]
class Solution {
public:
vector<vector<int> > zigzagLevelOrder(TreeNode *root) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
// result
vector<vector<int> > res;
if(NULL == root)return res;
// store nodes in queue
queue<vector<TreeNode*> > mQueue;
vector<TreeNode*> tmp;
tmp.push_back(root);
mQueue.push(tmp);
// level order
int level = 0;
while(!mQueue.empty()){
vector<int> levelRes;
vector<TreeNode*> levelNode;
// iterate
vector<TreeNode*> nodes = mQueue.front();
if(level % 2 == 0){
vector<TreeNode*>::iterator it;
for(it = nodes.begin(); it != nodes.end(); ++it){
levelRes.push_back((*it)->val);
}
}
else{
vector<TreeNode*>::reverse_iterator it;
for(it = nodes.rbegin(); it != nodes.rend(); ++it){
levelRes.push_back((*it)->val);
4000
}
}
vector<TreeNode*>::iterator it;
for(it = nodes.begin(); it != nodes.end(); ++it){
if((*it)->left != NULL){
levelNode.push_back((*it)->left);
}
if((*it)->right != NULL){
levelNode.push_back((*it)->right);
}
}
res.push_back(levelRes);
mQueue.pop();
if(levelNode.size() > 0){
mQueue.push(levelNode);
}
level++;
}
return res;
}
};
说明:版权所有,转载请注明出处。Coder007的博客
Given a binary tree, return the zigzag level order
traversal of its nodes' values. (ie, from left to right, then right
to left for the next level and alternate between).
For example:
Given binary tree
{3,9,20,#,#,15,7},
3 / \ 9 20 / \ 15 7
return its zigzag level order traversal as:
[ [3], [20,9], [15,7] ]
[Solution]
class Solution {
public:
vector<vector<int> > zigzagLevelOrder(TreeNode *root) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
// result
vector<vector<int> > res;
if(NULL == root)return res;
// store nodes in queue
queue<vector<TreeNode*> > mQueue;
vector<TreeNode*> tmp;
tmp.push_back(root);
mQueue.push(tmp);
// level order
int level = 0;
while(!mQueue.empty()){
vector<int> levelRes;
vector<TreeNode*> levelNode;
// iterate
vector<TreeNode*> nodes = mQueue.front();
if(level % 2 == 0){
vector<TreeNode*>::iterator it;
for(it = nodes.begin(); it != nodes.end(); ++it){
levelRes.push_back((*it)->val);
}
}
else{
vector<TreeNode*>::reverse_iterator it;
for(it = nodes.rbegin(); it != nodes.rend(); ++it){
levelRes.push_back((*it)->val);
4000
}
}
vector<TreeNode*>::iterator it;
for(it = nodes.begin(); it != nodes.end(); ++it){
if((*it)->left != NULL){
levelNode.push_back((*it)->left);
}
if((*it)->right != NULL){
levelNode.push_back((*it)->right);
}
}
res.push_back(levelRes);
mQueue.pop();
if(levelNode.size() > 0){
mQueue.push(levelNode);
}
level++;
}
return res;
}
};
说明:版权所有,转载请注明出处。Coder007的博客
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