Cod sursa(job #2753234)

Utilizator Andreea__Zavoiu Andreea Andreea__ Data 21 mai 2021 20:00:33
Problema Arbori de intervale Scor 30
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.62 kb
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("arbint.in");
ofstream fout("arbint.out");

int stree[400000], v[100000]; // segment tree

void constructST(int i, int st, int dr) {
    if (st == dr) {
        stree[i] = v[dr];
        return;
    }

    int mij = (st + dr) / 2;
    constructST (2*i, st, mij ); // fiul stang
    constructST (2*i+1, mij + 1, dr ); // fiul drept

    stree[i] = max( stree[2*i], stree[2 * i + 1] ); // in nod se alege maximul dintre cei 2 fii
}

int getMaxPeInterval(int i, int st, int dr, int x, int y)
{
    // If segment of this node is a part of the given range, then return the min of the segment
    if (x <= st && y >= dr)
        return stree[i];

    // If a part of this segment overlaps with the given range
    int mij = st + (dr - st) / 2;

    if (x > mij)
        return getMaxPeInterval(2*i+1, mij + 1, dr, x, y);
    else if (y <= mij)
        return getMaxPeInterval(2*i, st, mij, x, y);

    return max( getMaxPeInterval(2*i, st, mij, x, mij),  getMaxPeInterval(2*i+1, mij+1, dr, mij+1, y) );
}

int main()
{
    int n, m, a, b, op;
    fin >> n >> m;
    for (int i = 1 ; i <= n ; i++)
        fin >> v[i];

    constructST(1, 1, n); // construiesc arborele de intervale incepand cu nodul 1, pentru intervalul [1,n]

    for (int i = 0 ; i < m ; i++)
    {
        fin >> op >> a >> b;
        if(op == 0)
            fout << getMaxPeInterval(1, 1, n, a, b) << '\n';
        else { // op ==1  => valoarea de pe pozitia a devine b
            v[a] = b;
            constructST(1,1,n);
        }
    }

    return 0;
}