Cod sursa(job #2847643)

Utilizator Madalin_IonutFocsa Ionut-Madalin Madalin_Ionut Data 11 februarie 2022 10:34:51
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.48 kb
#include <bits/stdc++.h>
using namespace std;

/**
8 6
a = 25 42 8 15 0 0 0  13 55 16 67
0 5 12
2 25
2 90
1 7 7
1 2 8
2 241

*/
ifstream fin("aib.in");
ofstream fout("aib.out");
int aib[100003], n;

/// ret. suma pe intervalul [1..k]
int Suma(int k)
{
    int s = 0;
    while (k > 0)
    {
        s += aib[k];
        k = k - (k&-k);
    }
    return s;
}

void Update(int k, int val)
{
    while (k <= n)
    {
        aib[k] += val;
        k = k + (k & -k);
    }
}

/// caut binar cea mai din stanga pozitie
/// p in care Suma(p) >= val
int CautBin(int val)
{
    if (val < aib[1]) return -1;
    int st, dr, mid, p;
    st = 1; dr = p = n;
    while (st <= dr)
    {
        mid = (st + dr) / 2;
        if (Suma(mid) >= val)
        {
            p = mid;
            dr = mid - 1;
        }
        else st = mid + 1;
    }
    if (Suma(p) == val) return p;
    return -1;
}

int main()
{
    int i, k, Q, op, x, y;
    fin >> n >> Q;
    for (i = 1; i <= n; i++)
    {
        fin >> k;
        Update(i, k);
    }
    for (i = 1; i <= Q; i++)
    {
        fin >> op;
        if (op == 0)
        {
            fin >> k >> x;
            Update(k, x);
        }
        else if (op == 1)
        {
            fin >> x >> y;
            fout << Suma(y) - Suma(x - 1) << "\n";
        }
        else /// op == 2
        {
            fin >> x;
            fout << CautBin(x) << "\n";
        }
    }
    return 0;
}