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A Stepping Number is an integer such that all of its adjacent digits have an absolute difference of exactly 1. For example, 321 is a Stepping Number while 421 is not.
Given two integers low and high, find and return a sorted list of all the Stepping Numbers in the range [low, high] inclusive.
Example 1:
Input: low = 0, high = 21 Output: [0,1,2,3,4,5,6,7,8,9,10,12,21]
Constraints:
0 <= low <= high <= 2 * 10^9
如果一个整数上的每一位数字与其相邻位上的数字的绝对差都是 1，那么这个数就是一个「步进数」。
例如，321 是一个步进数，而 421 不是。
给你两个整数，low 和 high，请你找出在 [low, high] 范围内的所有步进数，并返回 排序后 的结果。
示例：
输入：low = 0, high = 21 输出：[0,1,2,3,4,5,6,7,8,9,10,12,21]
提示：
0 <= low <= high <= 2 * 10^9
Runtime: 152 ms
Memory Usage: 22.3 MB
1 class Solution { 2 var L:Int = 0 3 var S:[Int] = [Int]() 4 5 func countSteppingNumbers(_ low: Int, _ high: Int) -> [Int] { 6 self.L = high 7 var ans:[Int] = [Int]() 8 for i in 1...9 9 { 10 search(i) 11 } 12 if 0 >= low && 0 <= high 13 { 14 ans.append(0) 15 } 16 for i in S 17 { 18 if i >= low && i <= high 19 { 20 ans.append(i) 21 } 22 } 23 ans.sort() 24 return ans 25 } 26 27 func search(_ x:Int) 28 { 29 if x > L{return} 30 S.append(x) 31 let last:Int = x % 10 32 if last != 0 33 { 34 search(x * 10 + last - 1) 35 } 36 if last != 9 37 { 38 search(x * 10 + last + 1) 39 } 40 } 41 }