LeetCode 111. 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) {
          int left,right;
        if(root==null){
            return 0;
        }else if(root.left==null && root.right==null){
            return 1;
        }else if(root.left!=null && root.right!=null){
            left = minDepth(root.left);
            right =minDepth(root.right);
            return Math.min(left,right)+1;
        }else if(root.left==null){
           return minDepth(root.right)+1;
        }else {
            return minDepth(root.left)+1;
        }
    }
}