Cod sursa(job #3208758)

Utilizator andreipirjol5Andrei Pirjol andreipirjol5 Data 29 februarie 2024 20:29:35
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.13 kb
#include <fstream>
#include <vector>
#include <cmath>

using namespace std;

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

vector <int> aint;
int rightmax, n;
const int NMAX = 1e5;
int v[NMAX + 5];

void Allocate()
{
    int exp = log2(n);

    if((1 << exp) != n)
        exp++;

    aint.resize(2 * (1 << exp) + 5);
    rightmax = 1 << exp;
}

void build(int node = 1, int left = 1, int right = rightmax)
{
    if(left == right and left > n)
    {
        aint[node] = 0;
        return;
    }
    if(left == right)
    {
        aint[node] = v[left];
        return;
    }

    int mid = (left + right) / 2;

    build(2 * node, left, mid);
    build(2 * node + 1, mid + 1, right);

    aint[node] = max(aint[2 * node], aint[2 * node + 1]);
}

void update(int pos, int value, int node = 1, int left = 1, int right = rightmax)
{
    if(left == right and left > n)
    {
        aint[node] = 0;
        return;
    }

    if(left == right)
    {
        aint[node] = value;
        return;
    }

    int mid = (left + right) / 2;

    if(pos <= mid)
        update(pos, value, 2 * node, left, mid);
    if(pos > mid)
        update(pos, value, 2 * node + 1, mid + 1, right);

    aint[node] = max(aint[2 * node], aint[2 * node + 1]);
}

int query(int qleft, int qright, int node = 1, int left = 1, int right = rightmax)
{
    if(qleft <= left and right <= qright)
        return aint[node];

    int mid = (left + right) / 2, leftans = 0, rightans = 0;

    if(qleft <= mid)
    leftans = query(qleft, qright, 2 * node, left, mid);

    if(mid < qright)
    rightans = query(qleft, qright, 2 * node + 1, mid + 1, right);

    return max(leftans, rightans);
}

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

    Allocate();

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

    build();

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

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

    fin.close();
    fout.close();
    return 0;
}