Cod sursa(job #2916050)

Utilizator nstefanNeagu Stefan nstefan Data 27 iulie 2022 22:40:25
Problema Arbori indexati binar Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.35 kb
#include <bits/stdc++.h>
using namespace std;

ifstream fin("aib.in");
ofstream fout("aib.out");
int n, m;
vector<int> v(100002), w(100002);

void add(int pos, int val)
{
    v[pos] += val;
    while (pos <= n) {
        w[pos] += val;
        pos += (pos & -pos);
    }
}

int sum(int pos)
{
    int sum = 0;
    while (pos >= 1) {
        sum += w[pos];
        pos -= (pos & -pos);
    }
    return sum;
}

int main()
{
    fin >> n >> m;
    for (int i = 1; i <= n; i++) {
        fin >> v[i];
        w[i] = v[i];
    }

    // populate finwick
    for (int i = 1; i <= n; i++) {
        int p = i + (i & -i);
        if (p <= n) {
            w[p] += w[i];
        }
    }

    // answer queries
    while (m--) {
        int c;
        fin >> c;
        if (c == 0) {
            int a, b;
            fin >> a >> b;
            add(a, b);
        }
        if (c == 1) {
            int a, b;
            fin >> a >> b;
            fout << sum(b) - sum(a - 1) << '\n';
        }
        if (c == 2) {
            int a;
            fin >> a;
            int power = 1;
            for (; power <= n; power <<= 1)
                ;
            int index = 1;
            for (; power; power >>= 1)
                if (index + power <= n and sum(index + power) <= a)
                    index += power;
            fout << (v[index] == a ? index : -1) << '\n';
        }
    }
}