ForumPostEasy | Topcoder Archive

Problem Statement

In this problem we are using 24-hour time. That is, the first second of each day is 00:00:00 and the last second of each day is 23:59:59.

You are visiting an online forum. Whenever there is a post that has been made strictly less than 24 hours ago, the forum displays a human-readable message stating when it was made. There are three types of messages:

"few seconds ago", which means the post is made between 0 and 59 seconds ago, inclusive.
"X minutes ago", where X is an integer between 1 and 59, inclusive, which means the post is made between X minutes and X minutes 59 seconds ago, inclusive.
"X hours ago", where X is an integer between 1 and 23, inclusive, which means the post is made between X hours and X hours 59 minutes 59 seconds ago, inclusive.

You are given the String[]s exactPostTime and showPostTime, both with the same number of elements. For each valid index i you know the following information:

Post i was made strictly less than 24 hours ago.
The exact time of day when post i was made is exactPostTime[i].
The human-readable string currently displayed by the forum software about post i is showPostTime[i].

Given all the information above, what is the current time?

Return the answer in the format "HH:MM:SS". If there are multiple solutions, return the one that comes first lexicographically. If the information given to you is self-contradictory and there is no solution, return "impossible" instead.

Definition

Class:: ForumPostEasy
Method:: getCurrentTime
Parameters:: String[], String[]
Returns:: String
Method signature:: String getCurrentTime(String[] exactPostTime, String[] showPostTime)
(be sure your method is public)

Notes

The lexicographically smaller of two equally-long strings is the one that has a character with a smaller ASCII value at the first index at which they differ.

Constraints

exactPostTime will contain between 0 and 50 elements, inclusive.
Each element of exactPostTime will be formatted as HH:MM:SS where HH is a two-digit integer between 00 and 23, inclusive, and both MM and SS are two-digit integers between 00 and 59, inclusive.
exactPostTime and showPostTime will contain same number of elements.
Each element of showPostTime will have one of the formats described in problem statment.

Examples

```
{"12:12:12"}
```
```
{"few seconds ago"}
```
```
Returns: "12:12:12"
```
The current time is somewhere between 12:12:12 and 12:13:11, inclusive. The returned time is the lexicographically smallest one out of all these times.
```
{"23:23:23","23:23:23"}
```
```
{"59 minutes ago","59 minutes ago"}
```
```
Returns: "00:22:23"
```
Both posts were made on the previous day. The current time is a bit after midnight.
```
{"00:10:10","00:10:10"}
```
```
{"59 minutes ago","1 hours ago"}
```
```
Returns: "impossible"
```
Two posts made in the same second cannot have two different human-readable strings.

{"11:59:13","11:13:23","12:25:15"}

{"few seconds ago","46 minutes ago","23 hours ago"}

Returns: "11:59:23"

The post made at 12:25:15 was posted yesterday at that time of day.

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