* Definition for binary tree

* struct TreeNode {

*int val;

 TreeNode *left;

* TreeNode *right;

*TreeNode(int x) : val(x), left(NULL), right(NULL) {}

* };

--------------------------BFS方法-----------------------*/

class Solution {

public:

vector > levelOrderBottom(TreeNode *root) {

vector> result;

queue que;

if(root==NULL) return result; //这里不能返回NULL

que.push(root);

while(que.size()){

vector level; int n=que.size();

for(int i=0;i

TreeNode *temp=que.front();

que.pop();

level.push_back(temp->val);

if(temp->left!=NULL)que.push(temp->left);

if(temp->right!=NULL)que.push(temp->right);

}

result.push_back(level);

}

reverse(result.begin(),result.end());

return result;

}

};

--------------------------------------------------------------

------------------------DFS方法--------------------------

class Solution {

public:

int Height(TreeNode *root)   

  {       

 if(!root) return 0;     

   return max(Height(root->left),Height(root->right))+1;  

   }   

  vector> levelOrderBottom(TreeNode *root)     {

        vector> result(Height(root),vector());        

        if(!root) return result;       

         DFS(root,result.size()-1,result);         

          return result;           

   }   

  void DFS(TreeNode *root,int height,vector> &result)

     {

        if(!root)

            return;

        result[height].push_back(root->val);

        DFS(root->left,height-1,result);

        DFS(root->right,height-1,result);

     }   

};