LeetCode-in-Java
2437. Number of Valid Clock Times
Easy
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:
timeis a valid string of length5in 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 from0to9.
Solution
public class Solution {
public int countTime(String time) {
int[] counts = new int[] {3, 10, 0, 6, 10};
char[] ch = time.toCharArray();
int result = 1;
if (ch[0] == '2') {
counts[1] = 4;
}
if ((ch[1] - '0') > 3) {
counts[0] = 2;
}
if (ch[0] == '?' && ch[1] == '?') {
counts[0] = 1;
counts[1] = 24;
}
for (int i = 0; i < 5; i++) {
char ch1 = ch[i];
if (ch1 == '?') {
result *= counts[i];
}
}
return result;
}
}