线性三元组
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Description
一个线性三元组是指一个满足如下关系有序三元组(s1,s2,s3):s3-s2=s2-s1.如(1,2,3),(2,4,6),(14,21,28)都是满足条件的线性三元组. 对于给定的一个S(3 <= S <= 30)个有序的元素的集合(元素值在1..100间),请输出可以组成的线性三元组的数目.
Input Format
第二行:S个用空格隔开的整数.
Output Format
仅一行,包含一个整数,可以组成的线性三元组的数量,保证在长整形范围内..
Sample
input
7
1 2 3 4 6 8 9
output
5
Hint
时间限制：
空间限制：
20200810数组基本练习
- Status
- Done
- Rule
- ACM/ICPC
- Problem
- 12
- Start at
- 2020-8-10 9:48
- End at
- 2020-8-11 9:48
- Duration
- 24 hour(s)
- Host
-
admin
- Partic.
- 43
