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.

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public int minDepth(TreeNode root) {// Start typing your Java solution below// DO NOT write main() functionif(root == null)return 0;if(root.left == null && root.right == null)return 1;else if(root.left == null)return minDepth(root.right) + 1;else if(root.right == null)return minDepth(root.left) + 1;elsereturn Math.min(minDepth(root.left), minDepth(root.right)) + 1;}}