Cod sursa(job #2196582)

Utilizator Garen456Paun Tudor Garen456 Data 19 aprilie 2018 19:09:31
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.2 kb
#include <bits/stdc++.h>

using namespace std;
ifstream fin("aib.in");
ofstream fout("aib.out");
int a[100005],n,m;

int lsb(int x) // least significant bit
{
    return x & -x;
}

void Update(int pos,int val)
{
    while(pos<=n)
    {
        a[pos]+=val;
        pos+=lsb(pos);
    }
}

int Query(int pos)
{
    int sum=0;
    while(pos)
    {  sum=sum+a[pos];
        pos-=lsb(pos);
    }
   return sum;
}

int Search(int val)
{
    int BigBit,i;

    for( BigBit=1; BigBit < n; BigBit*=2 );

    for(i=0; BigBit ;  BigBit/=2 )
        if(  i+BigBit<=n )
           if( val >= a[ i + BigBit ]  )
           { val-= a[i+BigBit];
               i+=BigBit;
               if(!val) return i;
           }

    return -1;
}

int main()
{
    fin>>n>>m;
    int i,x,op,a,b;
    for(i=1 ; i<=n; ++i)
    { fin>>x;
        Update(i,x);
    }

    for(i=1; i<=m; ++i)
    { fin>>op;
        if(op==0)
        { fin>>a>>b;
            Update(a,b);
        }
        if(op==1)
        { fin>>a>>b;
            fout<<Query(b)-Query(a-1)<<"\n";
        }
        if(op==2)
        { fin>>a;
            fout<<Search(a)<<"\n";
        }
    }

    return 0;
}