2 人解决，7 人已尝试。
2 份提交通过，共有 18 份提交。
9.5 EMB 奖励。
单点时限: 2.0 sec
内存限制: 256 MB
A genetic code of the abstract primitivus (Primitivus recurencis) is a series of natural numbers K=(a_1,…,a_n). A feature of primitivus we call each ordered pair of numbers (l,r), which appears successively in the genetic code, i.e. there exists such i that l=a_i, r=a_i+1. There are no (p,p) features in a primitivus’ genetic code.
Task
Write a program which:
1.reads the list of the features,
2.computes the length of the shortest genetic code having given features,
3.writes the results.
In the first line of the input one positive integer number n is written. It is the number of different features of the primitivus. In each of the following n lines there is a pair of natural numbers l and r separated by a single space, 1 <= l <= 1000, 1 <= r <= 1000. A pair (l, r) is one of the primitivus’ features. The features do not repeat in the input file
Your program should write, in the first and only line, exactly one integer number equal to the length of the shortest genetic code of the primitivus, comprising the features .
12 2 3 3 9 9 6 8 5 5 7 7 6 4 5 5 1 1 4 4 2 2 8 8 6
15 hint: All the features from the file PIE.IN are written in the following genetic code: (8, 5, 1, 4, 2, 3, 9, 6, 4, 5, 7, 6, 2, 8, 6)
2 人解决，7 人已尝试。
2 份提交通过，共有 18 份提交。
9.5 EMB 奖励。