Cod sursa(job #2123481)

Utilizator IsacLucianIsac Lucian IsacLucian Data 6 februarie 2018 12:04:15
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.18 kb
#include <bits/stdc++.h>

using namespace std;

ifstream fin("aib.in");
ofstream fout("aib.out");

int aib[100005],n,m;

int Query(int p)
{
    int s=0;
    while(p>0)
    {
        s+=aib[p];
        p-=(p&(-p));
    }
    return s;
}

void Update(int p,int x)
{
    while(p<=n)
    {
        aib[p]+=x;
        p+=(p&(-p));
    }
}

//ret cea mai din stg poz p cu a1+a2+..+ap=s
int CautaPoz(int s)
{
    int st,dr,mid,p,suma;
    p=-1;
    st=1;dr=n;
    while(st<=dr)
    {
        mid=(st+dr)/2;
        suma=Query(mid);
        if(suma==s){p=mid;dr=mid-1;}
        else if(suma>s)dr=mid-1;
        else st=mid+1;
    }

    return p;
}

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

    int op,p,y;
    while(m--)
    {
        fin>>op;
        if(op==0)
        {
            fin>>p>>x;
            Update(p,x);
        }
        else if(op==1)
        {
            fin>>x>>y;
            fout<<Query(y)-Query(x-1)<<"\n";
        }
        else {
            fin>>p;
            fout<<CautaPoz(p)<<"\n";
        }
    }
    return 0;
}