Cod sursa(job #795280)

Utilizator radustn92Radu Stancu radustn92 Data 7 octombrie 2012 23:01:23
Problema Arbori indexati binar Scor 50
Compilator cpp Status done
Runda Arhiva educationala Marime 1.1 kb
#include <stdio.h>
#define NMAX 100005
int n,m,A[NMAX],aib[NMAX];
void read()
{
	scanf("%d%d",&n,&m);
	int i;
	for (i=1; i<=n; i++)
		scanf("%d",&A[i]);
}
int lsb(int x)
{
	return x & -x;
}
int suma(int poz)
{
	int i,s=0;
	for (i=poz; i>0; i-=lsb(i))
		s+=aib[i];
	return s;
}
void update(int poz,int val)
{
	int i;
	for (i=poz; i<=n; i+=lsb(i))
		aib[i]+=val;
}
int find(int val)
{
	int step,poz,act=0;
	for (step=1; step<=n; step<<=1);
	for (poz=0; step; step>>=1)
		if (poz+step<=n && act+aib[poz+step]<=val)
			poz+=step,act+=aib[poz];
	return poz;
}
void solve()
{
	int i,tip,x,y;
	for (i=1; i<=n; i++)
		update(i,A[i]);
	for (i=1; i<=m; i++)
	{
		scanf("%d",&tip);
		if (tip==0)
		{
			scanf("%d%d",&x,&y);
			update(x,y);
		}
		if (tip==1)
		{
			scanf("%d%d",&x,&y);
			printf("%d\n",suma(y)-suma(x-1));
		}
		if (tip==2)
		{
			scanf("%d",&x);
			y=find(x);
			if (suma(y)!=x)
				printf("-1\n");
			else
				printf("%d\n",y);
		}
	}
}
int main()
{
	freopen("aib.in","r",stdin);
	freopen("aib.out","w",stdout);
	read();
	solve();
	return 0;
}