Cod sursa(job #2282565)

Utilizator UnseenMarksmanDavid Catalin UnseenMarksman Data 14 noiembrie 2018 08:33:14
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.4 kb
#include <iostream>
#include <fstream>
#define maxn 100002
using namespace std;

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

int n, q;
int tree[maxn+2];

void update(int pos, int val)
{
    while(pos<=n)
    {
        tree[pos]+=val;
        pos+=(pos&-pos);
    }
}

int query(int pos)
{
    int sum=0;
    while(pos>0)
    {
        sum=sum+tree[pos];
        pos=pos-(pos&-pos);
    }
    return sum;
}

int idxsearch(int val)
{
    int i, bitmask;

    for(bitmask=1; bitmask<n; bitmask<<=1);

    for(i=0; bitmask; bitmask>>=1)
    {
        if(i+bitmask<=n)
        {
            if(val>=tree[i+bitmask])
            {
                i=i+bitmask;
                val=val-tree[i];
                if(!val)
                {
                    return i;
                }
            }
        }
    }
    return -1;
}

int main()
{
    int val, op, pos1, pos2;
    fin>>n>>q;
    for(int i=1; i<=n; i++)
    {
        fin>>val;
        update(i,val);
    }
    while(q--)
    {
        fin>>op;
        if(op==0)
        {
            fin>>pos1>>val;
            update(pos1,val);
        }
        else if(op==1)
        {
            fin>>pos1>>pos2;
            fout<<query(pos2)-query(pos1-1)<<'\n';
        }
        else
        {
            fin>>val;
            fout<<idxsearch(val)<<'\n';
        }
    }
    return 0;
}