class Solution {
public:
vector > res;
public:
void trval(TreeNode *root,int level)
{
if(root==NULL)
return;
if(level==res.size())
{
vector v;
res.push_back(v);
}
res[level].push_back(root->val);
trval(root->left,level+1);
trval(root->right,level+1);
}
vector > levelOrder(TreeNode *root) {
trval(root,0);
return res;
}
};
Binary Tree Level Order Traversal
原文：http://www.cnblogs.com/qiaozhoulin/p/4509910.html
