Cod sursa(job #615276)

Utilizator BitOneSAlexandru BitOne Data 9 octombrie 2011 09:02:20
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.01 kb
#include <fstream>
#include <cstdlib>
#define N_MAX 100011

using namespace std;
int N;
int v[N_MAX];
inline int Log2( int x ) { return 31-__builtin_clz(x); }
void Update( int xIndex, int xValue )
{
	for( ; xIndex <= N; xIndex+=( xIndex & -xIndex ) )
		v[xIndex]+=xValue;
}
int Sum( int xIndex )
{
	int sum;
	for( sum=0; xIndex; xIndex-=( xIndex & -xIndex ) )
		sum+=v[xIndex];
	return sum;
}
int Query( int idx, int k )
{
	for( int tidx, i=0; idx; idx>>=1 )
	{
		tidx=idx+i;
		if( tidx <= N )
		{
			if( v[tidx] > k )
				continue;
			if( k == v[tidx] )
				return tidx;
			k-=v[tidx];
			i=tidx;
		}
	}
	return -1;
}
int main( void )
{
	int M, i, x, op, a, b, idx;
	ifstream in( "aib.in" );
	in>>N>>M;
	idx=1<<Log2(N);
	for( i=1; i <= N; ++i )
	{
		in>>x;
		Update( i, x );
	}
	ofstream out( "aib.out" );
	for( ; M; --M )
	{
		in>>op;
		switch( op )
		{
			case 0 : in>>a>>b; Update( a, b ); break;
			case 1 : in>>a>>b; out<<( Sum(b)-Sum(a-1) )<<'\n'; break;
			case 2 : in>>a; out<<Query(idx, a)<<'\n';
		}
	}
	return EXIT_SUCCESS;
}