首页 > itarticle > leetcode题目:binary tree level order traversal

leetcode题目:binary tree level order traversal

admin 11月 11, 2020 0

Binary Tree Level Order Traversal:

Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).

class Solution {
private:
    void (TreeNode *root, vector<vector<int>> &coll, int level){
        
        if(level + 1 > coll.size())
            coll.push_back(vector<int>(1, root->val));
        //把当前节点的val插入到第level层
        else
            coll[level].push_back(root->val);
        //递归的处理左右子树
        if(root->left)
            helper(root->left, coll, level + 1);
        if(root->right)
            helper(root->right, coll, level + 1);
    }
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        vector<vector<int>> coll;
        if(root)
            helper(root, coll, 0);
        return coll;
    }
};