leetcode-Binary Tree Level Order Traversal II(2014.1.27)
此題可以遞歸?二叉樹是遞歸結構,層次遍歷則好像不是
/**
* 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> > levelOrderBottom(TreeNode *root) {
vector<vector<int>> path;
vector<vector<int>> vec;
vector<int> vec1;
queue<TreeNode*> stk;
if(root==NULL) return path;
TreeNode* cur=NULL;
int num1=1,num2=0;
stk.push(root);
while(stk.empty()!=true){
vec1.clear();
for(int i=0;i<num1;i++){
cur=stk.front();
vec1.push_back(cur->val);
stk.pop();
if(cur->left){
stk.push(cur->left);
num2++;
}
if(cur->right){
stk.push(cur->right);
num2++;
}
}
num1=num2;
num2=0;
vec.push_back(vec1);
}
while(vec.empty()!=true){
path.push_back(vec.back());
vec.pop_back();
}
return path;
}
};
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