题解 | #从上往下打印二叉树#
从上往下打印二叉树
https://www.nowcoder.com/practice/7fe2212963db4790b57431d9ed259701
/* struct TreeNode { int val; struct TreeNode *left; struct TreeNode *right; TreeNode(int x) : val(x), left(NULL), right(NULL) { } };*/ #include <cstddef> #include <queue> #include <vector> class Solution { public: vector<int> PrintFromTopToBottom(TreeNode* root) { vector<int> out; if (!root) { return out; } queue<TreeNode*> q;\ q.push(root); while (!q.empty()) { TreeNode* cur = q.front(); q.pop(); out.push_back(cur->val); if (cur->left) { q.push(cur->left); } if (cur->right) { q.push(cur->right); } } return out; } };
使用队列queue实现二叉树的层次遍历