luogu#P10490. Missile Defence System

    ID: 10121 远端评测题 2000ms 512MiB 尝试: 0 已通过: 0 难度: 5 上传者: 标签>搜索O2优化深度优先搜索 DFS剪枝

Missile Defence System

Problem Description

To play against the threats of malicious countries nearby, Country R has updated their missile defence system. The new type system can bring down a series of missiles as long as they are coming in ascending order by altitude or descending order by altitude.

Given the heights of a sequence of coming missiles, the general wants to know how many sets of the new type systems are needed to bring down all of them.

Input Format

The input consists of several test cases. The first line of each test case contains an integer n(1n50)n (1 \le n \le 50). The next line contains n different integers indicating the heights.

Output Format

For each test case output a single line containing the number of systems needed.For each test case output a single line containing the number of systems needed.

5 
3 5 2 4 1 
0
2

Hint

Two sets of systems are needed for the sample. One brings down 3, 4 and the other brings down 5, 2, 1.