Cod sursa(job #3299654)

Utilizator AxkyroMiron Victor Eusebiu Axkyro Data 8 iunie 2025 21:26:53
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.55 kb
#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

ifstream fin("arbint.in");
ofstream fout("arbint.out");

const int dim_max = 100000;          // dimensiune maxima
vector<int> arb(4 * dim_max + 5);    // arbore de intervale

int n, m;                            // numar elemente si operatii

// actualizeaza pozitia poz cu valoarea val
void update(int nod, int st, int dr, int poz, int val)
{
    if (st == dr)
    {
        arb[nod] = val;
        return;
    }

    int mij = (st + dr) / 2;

    if (poz <= mij)
        update(nod * 2, st, mij, poz, val);
    else
        update(nod * 2 + 1, mij + 1, dr, poz, val);

    arb[nod] = arb[nod * 2] > arb[nod * 2 + 1] ? arb[nod * 2] : arb[nod * 2 + 1];
}

// intoarce maximul pe intervalul [a, b]
int query(int nod, int a, int b, int st, int dr)
{
    if (a <= st && dr <= b) return arb[nod];

    int mij = (st + dr) / 2;
    int stanga = -1;
    int dreapta = -1;

    if (a <= mij)
        stanga = query(nod * 2, a, b, st, mij);

    if (mij < b)
        dreapta = query(nod * 2 + 1, a, b, mij + 1, dr);

    return stanga > dreapta ? stanga : dreapta;
}

int main()
{
    fin >> n >> m;

    for (int i = 1; i <= n; i++)
    {
        int val;
        fin >> val;
        update(1, 1, n, i, val);
    }

    while (m--)
    {
        int tip, x, y;
        fin >> tip >> x >> y;

        if (tip == 0)
            fout << query(1, x, y, 1, n) << '\n';
        else
            update(1, 1, n, x, y);
    }

    return 0;
}