102.Binary Tree Level Order Traversal

最新推荐文章于 2022-02-20 23:20:19 发布

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最新推荐文章于 2022-02-20 23:20:19 发布

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原文链接：http://www.cnblogs.com/smallredness/p/10676729.html

本文介绍了一种实现二叉树层次遍历的算法，提供了两种不同的实现方式：一种使用队列进行广度优先搜索，另一种采用递归方式进行深度优先搜索。这两种方法都能有效地按层次顺序遍历二叉树的所有节点。

class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        if (!root) return {};
        vector<vector<int>> res;
        queue<TreeNode*> q{{root}};
        while (!q.empty()) {
            vector<int> oneLevel;
            for (int i = q.size(); i > 0; --i) {
                TreeNode *t = q.front(); q.pop();
                oneLevel.push_back(t->val);
                if (t->left) q.push(t->left);
                if (t->right) q.push(t->right);
            }
            res.push_back(oneLevel);
        }
        return res;
    }
};

class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        vector<vector<int>> res;
        levelorder(root, 0, res);
        return res;
    }
    void levelorder(TreeNode* node, int level, vector<vector<int>>& res) {
        if (!node) return;
        if (res.size() == level) res.push_back({});
        res[level].push_back(node->val);
        if (node->left) levelorder(node->left, level + 1, res);
        if (node->right) levelorder(node->right, level + 1, res);
    }
};

转载于:https://www.cnblogs.com/smallredness/p/10676729.html