Package g0701_0800.s0753_cracking_the_safe

Class Solution

  • public class Solution
extends Object
    753 - Cracking the Safe.

    Hard

    There is a safe protected by a password. The password is a sequence of n digits where each digit can be in the range [0, k - 1].

    The safe has a peculiar way of checking the password. When you enter in a sequence, it checks the most recent n digits that were entered each time you type a digit.

    • For example, the correct password is "345" and you enter in "012345":
      • After typing 0, the most recent 3 digits is "0", which is incorrect.
      • After typing 1, the most recent 3 digits is "01", which is incorrect.
      • After typing 2, the most recent 3 digits is "012", which is incorrect.
      • After typing 3, the most recent 3 digits is "123", which is incorrect.
      • After typing 4, the most recent 3 digits is "234", which is incorrect.
      • After typing 5, the most recent 3 digits is "345", which is correct and the safe unlocks.

    Return any string of minimum length that will unlock the safe at some point of entering it.

    Example 1:

    Input: n = 1, k = 2

    Output: “10”

    Explanation: The password is a single digit, so enter each digit. “01” would also unlock the safe.

    Example 2:

    Input: n = 2, k = 2

    Output: “01100”

    Explanation: For each possible password:

    • “00” is typed in starting from the 4th digit.
    • “01” is typed in starting from the 1st digit.
    • “10” is typed in starting from the 3rd digit.
    • “11” is typed in starting from the 2nd digit.

    Thus “01100” will unlock the safe. “01100”, “10011”, and “11001” would also unlock the safe.

    Constraints:

    • 1 <= n <= 4
    • 1 <= k <= 10
    • 1 <= kn <= 4096

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • crackSafe

        public String crackSafe​(int n,
                        int k)