201604-1 折点计数

#include <iostream>
using namespace std;
const int N = 1010;
int n;
int q[N];
int main()
{
    cin >> n;
    for (int i = 0; i < n; i ++ ) cin >> q[i];
    int res = 0;
    for (int i = 1; i + 1 < n; i ++ )
    {
        int a = q[i - 1], b = q[i], c = q[i + 1];
        if (b > a && b > c || b < a && b < c)
            res ++ ;
    }
    cout << res << endl;
    return 0;
}