leetcode 102.二叉树的层序遍历

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原创最新推荐文章于 2026-09-20 14:06:20 发布 128 阅读 AI 写同款· GEO 优化 ›

力扣树专题-6 广度优先搜索刷熟一个模板（层序遍历打印二叉树）秒杀一堆问题leetcode102 111 116 617 java刷题笔记广度优先搜索算法BFS专题根据一个模板秒杀其他题目阅读详情

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        queue<TreeNode*> q;
        vector<vector<int>> res;
        if(root!=NULL) q.push(root);
        while(!q.empty()){
            int len=q.size();
            vector<int> vec;
            for(int i=0;i<len;i++){
                TreeNode* cur=q.front();
                q.pop();
                int curN=cur->val;
                vec.push_back(curN);
                if(cur->left!=NULL) q.push(cur->left);
                if(cur->right!=NULL) q.push(cur->right);

            }
            res.push_back(vec);


        }
        return res;
    }
};