Cod sursa(job #3133482)

Utilizator DragosStezarStezar Dragos Matei DragosStezar Data 25 mai 2023 19:29:36
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.66 kb
#include <bits/stdc++.h>

using namespace std;

#define N_MAX 100000

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

int tree[4 * N_MAX + 5];
int v[N_MAX + 5];
int n , m;
int cod;
int a , b , rez=INT_MIN;

void build(int node, int le, int ri) {
    if(le == ri) {
        tree[node] = v[le];
        return;
    }

    int mid = (le + ri) / 2;

    build(2 * node, le, mid);
    build(2 * node + 1, mid + 1, ri);

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

void update(int node, int le, int ri, int pos, int val) {
    if(le == ri) {
        tree[node] = val;
        return;
    }
    
    int mid = (le + ri) / 2;

    if(pos <= mid) {
        update(2 * node, le, mid, pos, val);
    }
    else {
        update(2 * node + 1, mid + 1, ri, pos, val);
    }

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

void query(int node, int le, int ri, int x, int y, int &ans) {
    if(x <= le && ri <= y) {
        ans = max(ans, tree[node]);
        return;
    }

    int mid = (le + ri) / 2;

    if(x <= mid) {
        query(2 * node, le, mid, x, y, ans);
    }
    if(y > mid) {
        query(2 * node + 1, mid + 1, ri, x, y, ans);
    }
}


int main(){
    f >> n >> m;
    for(int i=1 ; i<=n ; i++)
    {
        f >> v[i];
    }
    ///formam arborele de intervale
    build(1,1,n);
    for(int i=1 ; i<=m ; i++)
    {
        f >> cod;
        f >> a >> b;
        if(cod==0)
        {
            rez=INT_MIN;
            query(1,1,n,a,b,rez);
            g << rez << "\n";
        }
        else
        {
            update(1,1,n,a,b);
        }
    }
    return 0;
}