LeetCode Minimum Depth of Binary Tree

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.


 1 /**
 2  * Definition for binary tree
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public int minDepth(TreeNode root) {
12         if (root == null) {
13             return 0;
14         }
15         
16         if (root.left==null &&root.right==null) {
17             return 1;
18         }
19         if (root.left==null) {
20             return 1+minDepth(root.right);
21         }
22         if (root.right==null) {
23             return 1+minDepth(root.left);
24         }
25         return 1+Math.min(minDepth(root.left), minDepth(root.right));
26     }
27 }