LeetCode之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.

此題與Maximum Depth of Binary Tree有區別 謹慎！！！

For example,

    1
   / 
  2   

The result should be 2！！Not 1

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int minDepth(TreeNode *root) {
         if (!root) return 0;
         if (!root->left && !root->right) return 1;
		 if (!root->left)
			 return 1 + minDepth(root->right);
		 if (!root->right)
			 return 1 + minDepth(root->left);
		 int left, right;
		 left= minDepth(root->left);
		 right = minDepth(root->right);
		 return  1 + (left < right ? left : right);
    }
};