leetcode 386. Lexicographical Numbers

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Given an integer n, return 1 - n in lexicographical order.
For example, given 13, return: [1,10,11,12,13,2,3,4,5,6,7,8,9].
Please optimize your algorithm to use less time and space. The input size may be as large as 5,000,000.

  • my solution

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    return sorted([i for i in range(1,n+1)],key=str)

  • a clear solution:

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    def order(n):
        out = []
        cur = 1
        for i in range(1,n+1):
            out.append(cur)
            if cur*10 <= n:
                cur *= 10
            elif cur%10 != 9 and cur + 1 <= n:
                cur += 1
            else:
                while (cur//10)%10 == 9:
                    cur = cur//10
                cur = cur//10 + 1
        return out