LeetCode--Binary Tree Level Order Traversal II

标签：leetcode   traversal   bst   层次遍历   tree   

Given a binary tree, return the bottom-up level order traversal of its nodes‘ values. (ie, from left to right, level by level from leaf to root).

For example:
Given binary tree {3,9,20,#,#,15,7},

    3
   /   9  20
    /     15   7

return its bottom-up level order traversal as:

[
  [15,7],
  [9,20],
  [3]
]

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

/**
 * 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>> res;
        vector<vector<int>> temp;
        if(root==NULL)
            return res;
        queue<TreeNode*> use;
        use.push(root);
        int save = 1;
        while(save!=0)
        {
            int count = save;
            save = 0;
            vector<int> leve;
            while(count>0)
            {
                TreeNode* tree = use.front();
                use.pop();
                count--;
                leve.push_back(tree->val);
                if(tree->left != NULL)
                {
                    save++;
                    use.push(tree->left);
                }
                if(tree->right!=NULL)
                {
                    save++;
                    use.push(tree->right);
                }
            }
            temp.push_back(leve);
        }
        for(int i=temp.size()-1; i>=0; i--)
            res.push_back(temp[i]);
        return res;
    }
};

LeetCode--Binary Tree Level Order Traversal II

标签：leetcode   traversal   bst   层次遍历   tree   

原文地址：http://blog.csdn.net/shaya118/article/details/42709897