Cod sursa(job #2578950)

Utilizator mihneacazCazacu Mihnea mihneacaz Data 11 martie 2020 19:13:06
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.78 kb
#include <fstream>
#include <algorithm>

using namespace std;

const int NMAX = 100005;

ifstream cin("aib.in");
ofstream cout("aib.out");

long long v[NMAX], aib[NMAX];

void update(int poz, long long val, int n)
{
    for(int i = poz; i <= n; i += (i ^ (i - 1)) & i)
        aib[i] += val;
}

long long query(int poz)
{
    int sum = 0;
    for(int i = poz; i > 0; i -= (i ^ (i - 1)) & i)
        sum += aib[i];
    return sum;
}

int bs1(long long a, int n)
{
    int st = 1;
    int dr = n;
    int last = -1;
    while(st <= dr) {
        int med = (st + dr) / 2;
        int q = query(med);
        if(q <= a) {
            if(q == a)
                last = med;
            st = med + 1;
        }
        else
            dr = med - 1;
    }
    return last;
}

int bs2(long long a, int n)
{
    long long ca = a;
    int p = 1;
    for(; p <= n; p = p << 1);
    p = p >> 1;
    int ans = 0;
    for( ; p > 0; p = p >> 1) {
        if(ans + p <= n && aib[ans + p] < a) {
          ans += p;
          a -= aib[ans];
        }
    }
    ans++;
    if(query(ans) == ca)
        return ans;
    else
        return -1;
}


int main() {
    int n, m;
    cin >> n >> m;
    for(int i = 1; i <= n; ++i) {
        cin >> v[i];
        update(i, v[i], n);
    }
    for(int i = 1; i <= m; ++i) {
        int task;
        cin >> task;
        if(task == 0) {
            int poz;
            long long val;
            cin >> poz >> val;
            update(poz, val, n);
            continue;
        }
        if(task == 1) {
            int st, dr;
            cin >> st >> dr;
            cout << query(dr) - query(st - 1) << "\n";
            continue;
        }
        // task = 2
        long long a;
        cin >> a;
//        cout << bs1(a, n) << "\n";
        cout << bs2(a, n) << "\n";

    }
    return 0;
}