#P14101. [ZJCPC 2017] Problem Preparation

[ZJCPC 2017] Problem Preparation

题目描述

It's time to prepare the problems for the 1414-th Zhejiang Provincial Collegiate Programming Contest! Almost all members of SUA programming contest problem setter team brainstorm and code day and night to catch the deadline, and empty bottles of Marjar Cola\textit{Marjar Cola} litter the floor almost everywhere!

To make matters worse, one of the team member fell ill just before the deadline. So you, a brilliant student, are found by the team leader Dai to help the team check the problems' arrangement.

Now you are given the difficulty score of all problems. Dai introduces you the rules of the arrangement:

  • The number of problems should lie between 1010 and 1313 (both inclusive).
  • The difficulty scores of the easiest problems (that is to say, the problems with the smallest difficulty scores) should be equal to 11.
  • At least two problems should have their difficulty scores equal to 11.
  • After sorting the problems by their difficulty scores in ascending order, the absolute value of the difference of the difficulty scores between two neighboring problems should be no larger than 22. BUT, if one of the two neighboring problems is the hardest problem, there is no limitation about the difference of the difficulty scores between them. The hardest problem is the problem with the largest difficulty score. It's guaranteed that there is exactly one hardest problem.

The team members have given you lots of possible arrangements. Please check whether these arrangements obey the rules or not.

输入格式

There are multiple test cases. The first line of the input is an integer TT (1T1041 \le T \le 10^4), indicating the number of test cases. Then TT test cases follow.

The first line of each test case contains one integer nn (1n1001 \le n \le 100), indicating the number of problems.

The next line contains nn integers s1,s2,,sns_1, s_2, \dots, s_n (1000si1000-1000 \le s_i \le 1000), indicating the difficulty score of each problem.

We kindly remind you that this problem contains large I/O file, so it's recommended to use a faster I/O method. For example, you can use scanf/printf instead of cin/cout in C++.

输出格式

For each test case, output "Yes" (without quotes) if the arrangement follows the rules, otherwise output "No" (without quotes).

8
9
1 2 3 4 5 6 7 8 9
10
1 2 3 4 5 6 7 8 9 10
11
999 1 1 2 3 4 5 6 7 8 9
11
999 1 3 5 7 9 11 13 17 19 21
10
15 1 13 17 1 7 9 5 3 11
13
1 1 1 1 1 1 1 1 1 1 1 1 2
10
2 3 4 5 6 7 8 9 10 11
10
15 1 13 3 6 5 4 7 1 14
No
No
Yes
No
Yes
Yes
No
No

提示

The first arrangement has 99 problems only, which violates the first rule.

Only one problem in the second and the fourth arrangement has a difficulty score of 11, which violates the third rule.

The easiest problem in the seventh arrangement is a problem with a difficulty score of 22, which violates the second rule.

After sorting the problems of the eighth arrangement by their difficulty scores in ascending order, we can get the sequence {1,1,3,4,5,6,7,13,14,15}\{1, 1, 3, 4, 5, 6, 7, 13, 14, 15\}. We can easily discover that 137=6>2|13-7| = 6 > 2. As the problem with a difficulty score of 1313 is not the hardest problem (the hardest problem in this arrangement is the problem with a difficulty score of 1515), it violates the fourth rule.