LintCode 二叉树的最小深度

/**
 * Definition of TreeNode:
 * class TreeNode {
 * public:
 *     int val;
 *     TreeNode *left, *right;
 *     TreeNode(int val) {
 *         this->val = val;
 *         this->left = this->right = NULL;
 *     }
 * }
 */
class Solution {
public:
    /**
     * @param root: The root of binary tree.
     * @return: An integer
     */
    int minDepth(TreeNode *root) {
        // write your code here
        if(root==NULL)
         return 0;
         if(root->left==NULL&&root->right==NULL)
          return 1;
         int Left=minDepth(root->left);
         int  Right=minDepth(root->right);
         if(root->left==NULL)
         {
             return Right+1;
         }
          if(root->right==NULL)
         {
             return Left+1;
         }
        
            int depth=Left<Right?Left:Right;
            return depth+1;
    }
};