LintCode 155. 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
        return depth(root);
    }
    int depth(TreeNode* node)
    {
        if(node==NULL)
        {
            return 0;
        }
        if(!node->left) return depth(node->right)+1;
        if(!node->right) return depth(node->left)+1;
        return min(depth(node->left),depth(node->right))+1;
    }
};