Leetcode Problem 2437. Number of Valid Clock Times

2437. Number of Valid Clock Times

Leetcode Solutions

Permutations of Unknown Digits

  1. Initialize a variable result to 1, which will hold the total number of valid times.
  2. Check each character in the time string and determine the number of possibilities for each unknown digit based on its position:
    • If the first hour digit is unknown, it can be 0, 1, or 2 when the second digit is less than 4, otherwise 0 or 1.
    • If the second hour digit is unknown, it can be 0-9 if the first digit is 0 or 1, otherwise 0-3.
    • If the first minute digit is unknown, it can be 0-5.
    • If the second minute digit is unknown, it can be 0-9.
  3. Multiply result by the number of possibilities for each unknown digit.
  4. Return result as the total number of valid times.
UML Thumbnail

Recursive Exploration of Possibilities

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