LeetCode 104. Maximum Depth Of Binary Tree

104. Maximum Depth Of Binary Tree

Problem

Given the root of a binary tree, return its maximum depth.

A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Questions before reading example

1. DFS vs BFS
   • DFS 가 더 구현이 쉽기 때문에 DFS

Example

Input: root = [3,9,20,null,null,15,7]
Output: 3

Input: root = [1,null,2]
Output: 2

Solution

  class Solution {
  public int maxDepth(TreeNode root) {
    return dfs(root, 0);
  }

  private int dfs(TreeNode node, int currentDepth) {
    if (node == null) {
      return currentDepth;
    }

    return Math.max(dfs(node.left, currentDepth +1), dfs(node.right, currentDepth + 1));
  }
}

Spent time

Review

• DFS 기본 문제인데.. 문제해결에 시간이 생각보다 걸렸다.