minimum-depth-of-binary-tree java code

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 predepth(TreeNode root){        if(root==null){            return 0;        }        if(root.left==null){            return predepth(root.right)+1;        }        if(root.right==null){            return predepth(root.left)+1;        }        return Math.min(predepth(root.left),predepth(root.right))+1;    }    public int run(TreeNode root) {        return predepth(root);    }}