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 a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int minDepth(TreeNode root) {
            if(root==null)
                return 0;
            else if(root.left==null&&root.right==null)
                return 1;
            else if (root.left==null)
                return 1+minDepth(root.right);
            else if (root.right==null)
                return 1+minDepth(root.left);
            
            int l = minDepth(root.left);
            int r = minDepth(root.right);
            return l>r?r+1:l+1;
        }
}