Cod sursa(job #2485958)

Utilizator stefan1anubystefan popa stefan1anuby Data 2 noiembrie 2019 10:51:13
Problema Arbori indexati binar Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.42 kb
#include <fstream>

using namespace std;

int n,aib[100005];
ifstream cin("aib.in");
ofstream cout("aib.out");

void Update(int p, int x)
{
    while(p<=n)
    {
        aib[p]+=x;
        ///aflu cati biti de 0 sunt la finalul lui p(2 la put. nr biti)
        int i=1;
        while(p%(i*2)==0)
            i*=2;
        p+=i;
        ///sau fara while folosind p-=(p&(-p));
    }
}
/// suma ap[1..p]
int Suma(int p)
{
    int S=0;
    while(p>0)
    {
        S+=aib[p];
        p-=(p&(-p));
    }
    return S;
}
/// cauta cea mai din stanga pozitie poz cu suma a[1]+..a[poz]=s
int CautBin(int p,int s)
{
    int st,dr,poz,mij;
    st=1;dr=p;poz=-1;
    int suma;
    while(st<=dr)
    {
        mij=(st+dr)/2;
        suma=Suma(mij);
        if(suma==s)
        {
            poz=mij;
            dr=mij-1;
        }
        else if(suma>s) dr=mij-1;
        else st=mij+1;
    }
    return poz;
}
int main()
{
    int i,m,x,op,a,b;
    cin>>n>>m;
    for(i=1; i<=n; i++)
    {
        cin>>x;
        Update(i,x);
    }
    while(m--)
    {
        cin>>op;
        if(op==0)
        {
            cin>>a>>b;
            Update(a,b);
        }
        else if(op==1)
        {
            cin>>a>>b;
            cout<<Suma(b)-Suma(a-1)<<'\n';
        }
        else
        {
            cin>>a;
            cout<<CautBin(n,a)<<'\n';
        }
    }
    return 0;
}