题目描述
从上往下打印出二叉树的每个节点,同层节点从左至右打印。
思路:bfs
代码:
/* struct TreeNode { int val; struct TreeNode *left; struct TreeNode *right; TreeNode(int x) : val(x), left(NULL), right(NULL) { } };*/ class Solution { public: vector<int> PrintFromTopToBottom(TreeNode* root) { queue<TreeNode*>que; vector<int>res; if(root == nullptr) { return res; } que.push(root); res.push_back(root->val); while(!que.empty()) { TreeNode* pRoot=que.front(); que.pop(); if(pRoot->left) { que.push(pRoot->left); res.push_back(pRoot->left->val); } if(pRoot->right) { que.push(pRoot->right); res.push_back(pRoot->right->val); } } return res; } };