- Difficulty: Easy
- Tags: LeetCode, Easy, String, Enumeration, leetcode-2437, Math, O(1), Combinatorics
Problem
You are given a string of length 5
called time
, representing the current time on a digital clock in the format "hh:mm"
. The earliest possible time is "00:00"
and the latest possible time is "23:59"
.
In the string time
, the digits represented by the ?
symbol are unknown, and must be replaced with a digit from 0
to 9
.
Return an integer answer
, the number of valid clock times that can be created by replacing every ?
with a digit from 0
to 9
.
Example 1:
Input: time = "?5:00" Output: 2 Explanation: We can replace the ? with either a 0 or 1, producing "05:00" or "15:00". Note that we cannot replace it with a 2, since the time "25:00" is invalid. In total, we have two choices.
Example 2:
Input: time = "0?:0?" Output: 100 Explanation: Each ? can be replaced by any digit from 0 to 9, so we have 100 total choices.
Example 3:
Input: time = "??:??" Output: 1440 Explanation: There are 24 possible choices for the hours, and 60 possible choices for the minutes. In total, we have 24 * 60 = 1440 choices.
Constraints:
time
is a valid string of length5
in the format"hh:mm"
."00" <= hh <= "23"
"00" <= mm <= "59"
- Some of the digits might be replaced with
'?'
and need to be replaced with digits from0
to9
.