Binary Tree Level Order Traversal
问题:从上到下打印二叉树的每一行
分析:先搜出二叉树的高度,然后遍历高度,每次搜索一个高度
class Solution { public: int dfs(TreeNode *root) { if(root==NULL) return 0; if(root->left==NULL && root->right==NULL) return 1; return max(dfs(root->left),dfs(root->right))+1; } void Ddfs(TreeNode *root,int t,vector<int> &vec,int step) { if(step==t) vec.push_back(root->val); if(root->left) Ddfs(root->left,t,vec,step+1); if(root->right) Ddfs(root->right,t,vec,step+1); } vector<vector<int> > levelOrder(TreeNode *root) { int height=dfs(root); vector<vector<int> > vec1; for(int i=1;i<=height;i++) { vector<int> vec2; Ddfs(root,i,vec2,1); vec1.push_back(vec2); } return vec1; } };