[leetcode] Binary Tree Level Order Traversal

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

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

    3   / \  9  20    /  \   15   7

return its level order traversal as:

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

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

class Solution {public:    vector<vector<int> > levelOrder(TreeNode *root) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        queue<TreeNode *> level;        vector<vector<int> > container;        TreeNode *iroot;        vector<int> inner;        if(root==NULL)            return container;        level.push(root);        level.push(NULL);        inner.push_back(root->val);        container.push_back(inner);        inner.clear();        while(!level.empty()){            iroot=level.front();            level.pop();            if(iroot==NULL){                if(inner.size()==0)                    break;                container.push_back(inner);                inner.clear();                level.push(NULL);            }            else{                if(iroot->left){                    inner.push_back(iroot->left->val);                    level.push(iroot->left);                }                if(iroot->right){                    inner.push_back(iroot->right->val);                    level.push(iroot->right);                }            }        }        return container;    }};