Cod sursa(job #355167)

Utilizator Bit_MasterAlexandru-Iancu Caragicu Bit_Master Data 10 octombrie 2009 12:20:52
Problema Arbori de intervale Scor 40
Compilator cpp Status done
Runda Arhiva educationala Marime 1.19 kb
#include <cstdio>

int arb [1<<16], init [1<<16],x,y;

inline int max(int a, int b)
{
	if (a > b)
		return a;
	return b;
}

void construire(int st, int dr, int poz)
{
	if (st == dr)
	{
		init [st] = poz;
		return;
	}

	int mij = (st + dr)/2;

	construire (st, mij, 2*poz);
	construire (mij+1, dr, 2*poz+1);
}

void update(int poz, int val)
{
	int k = init [poz];
	arb [k] = val;

	for (k/=2; k > 0; k /= 2)
		arb [k] = max (arb [2*k], arb [2*k+1]);
}

int caut(int st, int dr, int poz)
{
	if (x <= st && dr <= y)
		return arb [poz];
	if (dr < x || st > y)
		return 0;
	int mij = (st + dr)/2;
	return max (caut(st,mij,2*poz), caut (mij+1,dr,2 * poz + 1));
}

int main()
{
	int n,m,nr;
	freopen ("arbint.in","r",stdin);
	freopen ("arbint.out","w",stdout);
	scanf ("%d%d",&n,&m);
	construire (1, n, 1);
	for (int i = 1; i <= n; ++i)
	{
		scanf ("%d",&nr);
		update (i, nr);
	}

	/*Citim operatiile.
	0 -> afisam maximul pe un interval;
	1 -> adaugam un element;
	*/

	int tip;

	for (int i = 1; i <= m; ++i)
	{
		scanf ("%d%d%d", &tip, &x, &y);

		if (tip == 0)
            printf ("%d\n",caut (1,n,1));
		else
			update (x, y);
	}

	return 0;
}