Cod sursa(job #3243859)

Utilizator maryyMaria Ciutea maryy Data 21 septembrie 2024 21:00:25
Problema Arbori indexati binar Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.57 kb
#include <bits/stdc++.h>

using namespace std;
ifstream in("aib.in");
ofstream out("aib.out");
const int NMAX=1e6;
long long aib[NMAX+1], n, m;
int max_p2;
void fenwick_add(int pos, int val)
{
    while(pos<=n)
    {
        aib[pos] += val;
        pos += (pos & -pos);
    }
}

long long fenwick_sum(int pos)
{
//    long long s = 0;
//    while (pos)
//    {
//        s += aib[pos];
//        pos = pos & (pos - 1);
//    }
//    return s;

    int ans=0;
    for(; pos>0; pos-=pos&(-pos))
        ans+=aib[pos];
    return ans;
}

long long fenwick_range_sum(int from, int to)
{
    return fenwick_sum(to) - fenwick_sum(from - 1);
}

int fenwick_bin_search(long long sum)
{
    int pos = 0;
    for (int interval = max_p2; interval; interval >>= 1)
    {
        if( (pos + interval <= n) && (aib[pos + interval] < sum))
        {
          sum -= aib[pos + interval];
          pos += interval;
        }
    }
    return pos + 1;
}

int main()
{
    int op, x, y;
    in>>n>>m;
    for(int i=1; i<=n; i++)
    {
        in>>x;
        fenwick_add(i, x);
    }
    max_p2 = n;
    while (max_p2 & (max_p2 - 1))
    {
        max_p2 &= (max_p2 - 1);
    }
    for(int i=1; i<=m; i++)
    {
        in>>op;
        if(op==0)
        {
            in>>x>>y;
            fenwick_add(x, y);
        }
        if(op==1)
        {
            in>>x>>y;
            out<<fenwick_range_sum(x, y)<<'\n';
        }
        if(op==2)
        {
            in>>x;
            out<<fenwick_bin_search(x)<<'\n';
        }
    }
}