Cod sursa(job #807057)

Utilizator alex_unixPetenchea Alexandru alex_unix Data 3 noiembrie 2012 23:40:15
Problema Arbori de intervale Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.65 kb

#include <cstdio>

const int MAX_SIZE(100001);

int it [MAX_SIZE << 1];
int values [MAX_SIZE];

int n, m;

inline void read (void)
{
	std::scanf("%d%d",&n,&m);
	for (int *iterator(values + 1), *end(values + n) ; iterator <= end ; ++iterator)
		std::scanf("%d",iterator);
}

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

void build (int index, int left, int right)
{
	int middle((left + right) >> 1);
	if (left == right)
	{
		it[index] = values[middle];
		return;
	}
	build(index << 1,left,middle);
	build((index << 1) + 1,middle + 1,right);
	it[index] = max(it[index << 1],it[(index << 1) + 1]);
}

void update (int index, int left, int right, int position, int value)
{
	int middle((left + right) >> 1);
	if (left == right)
	{
		it[index] = value;
		return;
	}
	if (position <= middle)
		update(index << 1,left,middle,position,value);
	else
		update((index << 1) + 1,middle + 1,right,position,value);
	it[index] = max(it[index << 1],it[(index << 1) + 1]);
}

int query (int index, int left, int right, int ql, int qr)
{
	int middle((left + right) >> 1);
	if (ql <= left && right <= qr)
		return it[index];
	int result(0);
	if (ql <= middle)
		result = max(result,query(index << 1,left,middle,ql,qr));
	if (qr > middle)
		result = max(result,query((index << 1) + 1,middle + 1,right,ql,qr));
	return result;
}

int main (void)
{
	std::freopen("arbint.in","r",stdin);
	std::freopen("arbint.out","w",stdout);
	read();
	build(1,1,n);
	int operation, a, b;
	do
	{
		std::scanf("%d%d%d",&operation,&a,&b);
		if (operation)
			update(1,1,n,a,b);
		else
			std::printf("%d\n",query(1,1,n,a,b));
		--m;
	}
	while (m);
	std::fclose(stdin);
	std::fclose(stdout);
	return 0;
}