【leetcode】967. Numbers With Same Consecutive Differences

题目如下：

Return all non-negative integers of length N such that the absolute difference between every two consecutive digits is K.

Note that every number in the answer must not have leading zeros except for the number 0 itself. For example, 01 has one leading zero and is invalid, but 0 is valid.

You may return the answer in any order.

Example 1:

Input: N = 3, K = 7
Output: [181,292,707,818,929]
Explanation: Note that 070 is not a valid number, because it has leading zeroes.

Example 2:

Input: N = 2, K = 1
Output: [10,12,21,23,32,34,43,45,54,56,65,67,76,78,87,89,98]

Note:

1. 1 <= N <= 9
2. 0 <= K <= 9

解题思路：题目本身很简单，利用BFS/DFS都可以。但是有两点要注意的，一是K = 0 的情况会造成重复（+0和-0的值一样），二是N等于1的时候，别忘了0也是其中一个结果。

解题思路：

class Solution(object):
    def numsSameConsecDiff(self, N, K):
        """
        :type N: int
        :type K: int
        :rtype: List[int]
        """
        res = []
        for i in range(1,10):
            queue = [str(i)]
            while len(queue) > 0:
                item = queue.pop(0)
                if len(item) == N:
                    res.append(item)
                    continue
                last = int(item[-1])
                if (last - K) >= 0:
                    queue.append(item + str(last - K))
                if K != 0 and abs(last + K) < 10:
                    queue.append(item + str(last + K))
        if N == 1:
            res.insert(0,'')
        return [int(i) for i in res]