LeetCode - 111. Minimum Depth of Binary Tree(Binary Tree, DFS, BFS, Tree)*

문제

Given a binary tree, find its minimum depth.
The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
Note: A leaf is a node with no children.

https://leetcode.com/problems/minimum-depth-of-binary-tree/description/

Example 1:

Input: root = [3,9,20,null,null,15,7]
Output: 2

Example 2:

Input: root = [2,null,3,null,4,null,5,null,6]
Output: 5

풀이

class Solution {
    public int minDepth(TreeNode root) {
        if(root == null) return 0;
        int left = minDepth(root.left);
        int right = minDepth(root.right);
        return (left==0||right==0) ? left+right+1 : Math.min(left,right)+1;
    }
}