Package g0701_0800.s0753_cracking_the_safe

Class Solution

java.lang.Object
g0701_0800.s0753_cracking_the_safe.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 Details

    • Solution

      public Solution()

  • Method Details

    • crackSafe

      public String crackSafe(int n, int k)