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/* -----------------------
Autor: Tomasz Boguslawski
-------------------------- */
#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<fstream>
#include<iomanip>
#include<string>
#include<sstream>
#include<cstring>
#include<map>
#include<vector>
#include<set>
#include<queue>
#include<algorithm>
#include <fstream>
#include<math.h>

#define LL long long
#define FOR(x, b, e) for(LL x = b; x <= (e); x++)
#define FORS(x, b, e, s) for(LL x = b; x <= (e); x+=s)
#define FORD(x, b, e) for(LL x = b; x >= (e); x--)
#define VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define DEBUG if (debug)
#define MIN(a,b) ((a>b)?b:a)
#define MAX(a,b) ((a>b)?a:b)

using namespace std;

int n;
LL p[50100];

LL a[50100]; // last leg up, original value
LL b[50100]; // last leg down, original value
LL c[50100]; // last leg up, changed value - big
LL d[50100]; // last leg down, changed value - small

/// MAIN
int main(int argc, char* argv[])
{
    // magic formula, which makes streams work faster:
	ios_base::sync_with_stdio(0);
	cin >> n;
	FOR(i,1,n) cin >> p[i];
	c[2] = 1; d[2] = 1;
	if (p[2]>p[1]) { a[2]=0; b[2]=1; }
	else if (p[2]<p[1]) { a[2]=1; b[2]=0; }
	else { a[2]=1; b[2]=1; };
	for (int i=3; i<=n; i++)
	{
	    a[i] = d[i-1];
	    if (p[i-1]<p[i]) if (b[i-1] < a[i]) a[i]=b[i-1];
	    b[i] = c[i-1];
	    if (p[i-1]>p[i]) if (a[i-1]<b[i]) b[i]=a[i-1];
	    c[i] = 1 + b[i-1];
	    if (d[i-1] < b[i-1]) c[i] = 1 + d[i-1]; // not necessary?
	    d[i] = 1 + a[i-1];
	    if (c[i-1] < a[i-1]) d[i] = 1 + c[i-1]; // not necessary?
	}
	LL opt = a[n];
	if (b[n] < opt) opt = b[n];
	if (c[n] < opt) opt = c[n];
	if (d[n] < opt) opt = d[n];
	cout << opt << '\n';
	return 0;
}