Cod sursa(job #2770901)

Utilizator andrei_C1Andrei Chertes andrei_C1 Data 23 august 2021 23:26:39
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.45 kb
#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
using namespace std;
ifstream fin("aib.in");
ofstream fout("aib.out");
int N, M;
vector<int>v, aib;
void update(int p, int v) {
    for(int i = p; i <= N; i += lsb(i)) {
        aib[i] += v;
    }
}
int query(int p) {
    int ret = 0;
    for(int i = p; i >= 1; i -= lsb(i)) {
        ret += aib[i];
    }
    return ret;
}
int main() {
    fin >> N >> M;
    v = vector<int>(N + 4);
    aib = vector<int>(N + 4);
    for(int i = 1; i <= N; i++) {
        fin >> v[i];
        update(i, v[i]);
    }
    for(int i = 1, q, a, b; i <= M; i++) {
        fin >> q;
        if(q == 0) {
            fin >> a >> b;
            update(a, b);
        } else if(q == 1) {
            fin >> a >> b;
            fout << query(b) - query(a - 1) << '\n';
        } else if(q == 2) {
            fin >> a;
            long long sum = 0, pos = 0, step, ans = -1;
            int LGN = __lg(N);
            for(int i = LGN; i >= 0; i--) {
                if(pos + (1 << i) <= N) {
                    if(sum + aib[pos + (1 << i)] < a) {
                        sum += aib[pos + (1 << i)];
                        pos += (1 << i);
                    } else if(sum + aib[pos + (1 << i)] == a) {
                        ans = pos + (1 << i);
                        break;
                    }
                }
            }
            fout << ans << '\n';
        }
    }
    return 0;
}