Cod sursa(job #2916974)

Utilizator florinrafiliuRafiliu Florin florinrafiliu Data 2 august 2022 16:07:53
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.44 kb
#include <iostream>
#include <fstream>
using namespace std;

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

const int maxN = 1e5 + 5;

int arb[4 * maxN], v[maxN];

void build (int k, int st, int dr) {
    if(st == dr)
        arb[k] = v[st];
    else {
        int mij = (st + dr) / 2;

        build(k * 2, st, mij);
        build(k * 2 + 1, mij + 1, dr);

        arb[k] = max(arb[k*2], arb[k*2+1]);
    }
}

void update(int poz, int val, int k, int st, int dr) {
    if(st == dr) {
        arb[k] = val;
    } else {
        int mij = (st + dr) / 2;

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

        arb[k] = max(arb[k*2], arb[k*2+1]);
    }
}

int query (int l, int r, int k, int st, int dr) {
    if(l > r) return 0;
    if(l <= st && dr <= r) {
        return arb[k];
    }
    int mij = (st + dr) / 2;

    return max(query(l, min(mij, r), k*2, st, mij),
               query(max(l, mij+1), r, k*2+1, mij+1, dr));
}

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

    for(int i = 1; i <= n; ++i)
        fin >> v[i];

    build(1, 1, n);

    for(int i = 1; i <= m; ++i) {
        int op; fin >> op;
        int a, b; fin >> a >> b;

        if(op == 0) {
            fout << query(a, b, 1, 1, n) << "\n";
        } else {
            update(a, b, 1, 1, n);
        }
    }

    return 0;
}