LeetCode - 102. Binary Tree Level Order Traversal

题目

LeetCode - 102. Binary Tree Level Order Traversal

题目链接

https://leetcode.com/problems/binary-tree-level-order-traversal/

解题思路

本题采取简单思路，先求树的最大深度是为确定适合的ans大小，然后常规的深度优先遍历。

解题源码

/**
 * 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:
    
    int maxheight = INT_MIN;
    int findMaxHeight(TreeNode* root){
        if(!root) return 0;
        else return max(findMaxHeight(root->left), findMaxHeight(root->right)) + 1;
    }
    
    void dfs(vector<vector<int>>& v, TreeNode* root, int height){
        if(!root) return ;
        v[height].push_back(root->val);
        dfs(v, root->left, height + 1);
        dfs(v, root->right, height + 1);
    }
    
    vector<vector<int>> levelOrder(TreeNode* root) {
        int mh = findMaxHeight(root);
        vector<vector<int> > ans(mh);
        dfs(ans, root, 0);
        return ans;
    }
};