剑指offer | 从上往下打印二叉树 | 28

目录

• 思路分析

思路分析

这个打印就是BFS的搜索,就是写一个BFS的模板

cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    vector<int> levelOrder(TreeNode* root) {
        vector<int> res;
        if(!root)return res;
        queue<TreeNode*> q;
        q.push(root);
        while(q.size()){
            auto t = q.front();
            q.pop();
            res.push_back(t->val);
            if(t->left)q.push(t->left);
            if(t->right)q.push(t->right);
        }
        return res;
    }
};

python

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def levelOrder(self, root: TreeNode) -> List[int]:
        from queue import deque
        res =[]
        if not root:return res
        q = deque()
        q.append(root)
        while len(q):
            t = q[0]
            q.popleft()
            res.append(t.val)
            if t.left:q.append(t.left)
            if t.right:q.append(t.right)
        return res