Cod sursa(job #3366819)

Utilizator robert_dumitruDumitru Robert Ionut robert_dumitru Data 4 octombrie 2026 15:03:26
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.54 kb
#include <fstream>

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

int n, m;
int aint[400005], a[100005];

void buildAint(int k, int st, int dr) {
    if (st == dr) {
        aint[k] = a[st];
    }
    else {
        int mid = (st + dr) / 2;
        buildAint(2 * k, st, mid);
        buildAint(2 * k + 1, mid + 1, dr);
        aint[k] = std::max(aint[2 * k], aint[2 * k + 1]);
    }
}

void update(int k, int st, int dr, int poz, int val) {
    if (st == dr) {
        aint[k] = val;
    }
    else {
        int mid = (st + dr) / 2;
        if (poz <= mid) {
            update(2 * k, st, mid, poz, val);
        }
        else {
            update(2 * k + 1, mid + 1, dr, poz, val);
        }
        aint[k] = std::max(aint[2 * k], aint[2 * k + 1]);
    }
}

int query(int k, int st, int dr, int x, int y) {
    if (x <= st && dr <= y) {
        return aint[k];
    }
    int mid = (st + dr) / 2;
    if (y <= mid) {
        return query(2 * k, st, mid, x, y);
    }
    else if (mid < x) {
        return query(2 * k + 1, mid + 1, dr, x, y);
    }
    return std::max(query(2 * k, st, mid, x, y), query(2 * k + 1, mid + 1, dr, x, y));
}

int main() {
    int q, x, y;
    fin >> n >> m;
    for (int i = 1; i <= n; i++) {
        fin >> a[i];
    }

    buildAint(1, 1, n);

    for (int i = 1; i <= m; i++) {
        fin >> q >> x >> y;
        if (q == 0) {
            fout << query(1, 1, n, x, y) << "\n";
        }
        else {
            update(1, 1, n, x, y);
        }
    }
}