Sequential Digits

#1. Brute Force
class Solution:
    def sequentialDigits(self, low: int, high: int) -> List[int]:
        res = []
        #s = '0123456789'
        n = len(str(low))
        #fix the size (2 to 9)
        for i in range(n,10):
            #fix the starting digit
            for j in range(1, 10-i+1):
                #build the number with sequential digits
                #num = int(s[j:i+j])
                num = 0
                for k in range(i):
                    num = (num<<3)+(num<<1)+j+k
                if num>high:
                    return res
                if num>=low:
                    res.append(num)
        return res

#2. BFS
class Solution:
    def sequentialDigits(self, low: int, high: int) -> List[int]:
        ans = []
        queue = deque(range(1, 9))
        while queue:
            curr = queue.popleft()
            if (rem := curr%10) != 9:
                num = curr*10+rem+1
                if num > high:
                    return ans
                queue.append(num)
                if num >= low:
                    ans.append(num)
        return ans