Numbers With Same Consecutive Differences

Return allnon-negativeintegers of lengthNsuch that the absolute difference between every two consecutive digits isK.

Note thateverynumber in the answermust nothave leading zerosexceptfor the number0itself. For example,01has one leading zero and is invalid, but0is 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 <= N <= 9
0 <= K <= 9

分析

最后一个digit， lastdigit+k<10 and lastdigit-k>=0.不是用abs这里

class Solution:
    def numsSameConsecDiff(self, N, K):
        """
        :type N: int
        :type K: int
        :rtype: List[int]
        """

        cur = {i for i in range(10)}
        for i in range(1,N):
            temp = set()
            for j in cur:                
                lastdigit = j%10                                    
                if j > 0 and lastdigit +K<10:
                    temp.add(j*10+lastdigit +K) 
                if j > 0 and lastdigit -K>=0:
                    temp.add(j*10+lastdigit -K)    

            cur = temp

        return list(cur)

简化版

        cur = range(10)
        for i in range(1,N):
            cur = {i*10+y for i in cur for y in [i%10+K,i%10-K] if i and 0<=y<10}
        return list(cur)