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 a binary tree node. 3  * public class TreeNode { 4  *     int val; 5  *     TreeNode left; 6  *     TreeNode right; 7  *     TreeNode(int x) { val = x; } 8  * } 9  */10 class Solution {11     public int minDepth(TreeNode root) {12         if(root == null) return 0;13         int left = minDepth(root.left);14         int right = minDepth(root.right);15         return (left == 0 || right == 0) ? left + right + 1: Math.min(left,right) + 1;16     }17 }