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102. 二叉树的层序遍历.cpp
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102. 二叉树的层序遍历.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>> levelOrder(TreeNode* root) {
queue<TreeNode*>q;
q.push(root);
vector<vector<int>>ans;
while(!q.empty()){
int size=q.size();
vector<int>el;
for(int i=0;i<size;i++){
TreeNode* temp=q.front();
q.pop();
if(temp!=NULL){
el.push_back(temp->val);
if(temp->left) q.push(temp->left);
if(temp->right) q.push(temp->right);
}
}
if(el.size()!=0)
ans.push_back(el);
}
if(ans.size()!=0)
return ans;
return {};
}
};