Editorial for Max's Anger Contest Series 2 P4 - Number Anger

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Author: maxcruickshanks

Subtask 1

Brute force each number in [1, R] and count it if it has D consecutive digits.

Time Complexity: \mathcal{O}(R \log_{10}(R))

Subtask 2

Realize that this is a digit dynamic programming problem and can have a memoized state based on the index and other properties.

Many states can capture all the required information, but the reference solution used

  • the current index,
  • whether there have been D consecutive digits,
  • whether there has been a digit besides 0,
  • whether the current number is equal to R so far,
  • the count of consecutive digits,
  • and the current digit.

Time Complexity: \mathcal{O}(\log_{10}(R)D)


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