Walking Boy
InterviewTime limit2sMemory limit1024 MB
Given the minutes when messages were sent, decide whether two non-overlapping 120-minute walks fit in the gaps, with walks allowed to touch messages.
- Level
Easy3 of 10
- Topics
- Greedy, Implementation
- Solved
- No attempts yet
Problem
One of the SWERC judges has a dog named Boy. Besides being a good competitive programmer, Boy loves fresh air, so she wants to be walked at least twice a day. Walking Boy requires consecutive minutes. Two walks cannot overlap, but one can start as soon as the previous one has finished.
Boy before and after getting ACCEPTED on this problem. Today, the judge sent messages to the SWERC Discord server. The -th message was sent minutes after midnight. You know that, when walking Boy, the judge does not send any messages, but he can send a message right before or right after a walk. Is it possible that the judge walked Boy at least twice today? A day has minutes, and a walk is considered to happen today if it starts at a minute and ends right before a minute . In that case, it must hold that and, for every , either or .
Input
The first line contains an integer (), the number of test cases. The descriptions of the test cases follow. The first line of each test case contains an integer (), the number of messages sent by the judge. The second line of each test case contains integers (), the times at which the messages were sent, in minutes elapsed from midnight.
Output
For each test case, output one line containing YES if Boy could have been walked at least twice, and NO otherwise.
Hint
In the first test case, the judge sent a message at each time that is a multiple of 100, excluding 0. Boy could not have been walked even once. In the second test case, the times are the same as above, but 500 and 1000 are missing. The judge could have walked Boy, for instance, during the time intervals and . The situation is illustrated in the picture below, where the walks are represented by green intervals.
In the third test case, the times are the same as in the first test case, but 1000 is missing. The judge could have walked Boy at most once. In the fourth test case, Boy could have been walked during the time intervals and . 