【关关的刷题日记56】Leetcode 107 Binary Tree Level Order Traversal II

class Solution {public:
    vector<vector<int>> levelOrderBottom(TreeNode* root) {
        vector<vector<int> >store;
        if(root==nullptr)
            return store;
        vector<TreeNode*>bfs;
        bfs.push_back(root);      
        int n=1, count=0;
        while(!bfs.empty())
        {
            vector<int>re;
            for(int i=0; i<n; i++)
            {
                TreeNode *temp=bfs[0];
                bfs.erase(bfs.begin());
                re.push_back(temp->val);
                if(temp->left)
                {
                    bfs.push_back(temp->left);
                    count++;    
                }
                if(temp->right)
                {
                    bfs.push_back(temp->right);
                    count++;
                }
            }
                store.push_back(re);
                n=count;
                count=0;    
        }
        for(int i=0; i<store.size()/2; i++)
        {
            swap(store[i], store[store.size()-1-i]);
        }
        return store;
    }};