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

返回長度為n的所有非負整數，使每兩個連續數字之間的絕對差為k。

註意，答案中的每個數字都不能有前導零，除了數字0本身。例如，01有一個前導零，它是無效的，但0是有效的。

您可以按任何順序返回答案。

例1：

輸入：n=3，k=7

輸出：【181292707818929】

說明：請註意，070不是有效數字，因為它有前導零。

例2：

輸入：n=2，k=1

輸出：【10、12、21、23、32、34、43、45、54、56、65、67、76、78、87、89、98】

註：

1. 1 <n= 9
2. 0 <= k<＝9

28ms

 1 class Solution {
 2     var v:[Int] = [Int]()
 3
 
     var n:Int = 0
 4     var k:Int = 0
 5     var val:Int = 0
 6     func numsSameConsecDiff(_ N: Int, _ K: Int) -> [Int] {
 7         if N == 1
 8         {
 9             for i in 0...9
10             {
11                 v.append(i)
12             }
13             return v
14         }
15         n = N
16         k = K
17         val = 0
18         dfs(0,0)
19         v = v.sorted(by:>)
20         return v
21     }
22     
23     func dfs(_ cur:Int,_ pr:Int)
24     {
25         if cur == n
26         {
27             v.append(val)
28             return
29         }
30         for i in 0...9
31         {
32             if cur == 0
33             {
34                 if i != 0
35                 {
36                     val = i
37                     dfs(cur + 1,i)
38                 }
39             }
40             else
41             {
42                 val *= 10 
43                 val += i
44                 if abs(pr - i) == k
45                 {
46                     dfs(cur + 1, i)
47                 }
48                 val -= i
49                 val /= 10
50             }
51         }
52     }
53 }

[Swift Weekly Contest 117]LeetCode967. 具有相同連續差異的數字 | Numbers With Same Consecutive Differences