Cod sursa(job #2705954)

Utilizator DragosC1Dragos DragosC1 Data 13 februarie 2021 16:22:16
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.55 kb
#include <fstream>
using namespace std;

int n, q;
int a[100001];
int ai[100001 * 2];

const int Inf = 1e9 + 1;

ifstream f("arbint.in");
ofstream g("arbint.out");

void read() {
    int i;
    f >> n >> q;
    for (i = 1; i <= n; i++)
        f >> a[i];
}

void buildTree(int ind, int is, int id) {
    if (is == id) {
        ai[ind] = a[is];
        return;
    }

    int mij = (is + id) / 2;

    buildTree(ind * 2, is, mij);
    buildTree(ind * 2 + 1, mij + 1, id);

    ai[ind] = max(ai[ind * 2], ai[ind * 2 + 1]);
}

int querry(int ind, int is, int id, int qs, int qd) {
    if (is > qd || id < qs)
        return 0;
    
    if (is >= qs && id <= qd)
        return ai[ind];

    int mij = (is + id) / 2;

    int s = querry(ind * 2, is, mij, qs, qd);
    int d = querry(ind * 2 + 1, mij + 1, id, qs, qd);

    return max(s, d);

}

void update(int ind, int is, int id, int qind) {
    if (is == id) {
        ai[ind] = a[is];
        return;
    }

    int mij = (is + id) / 2;

    if (mij >= qind) update(ind * 2, is, mij, qind);
    else update(ind * 2 + 1, mij + 1, id, qind);

    ai[ind] = max(ai[ind * 2], ai[ind * 2 + 1]);

}

void solve() {
    int i, op, x, y;
    for (i = 0; i < q; i++) {
        f >> op >> x >> y;
        if (op == 0) 
            g << querry(1, 1, n, x, y) << '\n';
        else {
            a[x] = y;
            update(1, 1, n, x);
        }
    }
    f.close();
    g.close();
}

int main() {
    read();
    buildTree(1, 1, n);
    solve();
    return 0;
}