Cod sursa(job #3367170)

Utilizator Lapush05alexandru Lapush05 Data 6 octombrie 2026 12:04:53
Problema Arbori de intervale Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.73 kb
#include <bits/stdc++.h>
using namespace std;

const int NMAX = 1e5;
int aint[4 * NMAX + 1];
int v[NMAX + 1];

void build(int node, int st, int dr) {
    if(st == dr) {
        aint[node] = v[st];
    } else {
        int mid = (st + dr) / 2;
        build(2 * node, st, mid);
        build(2 * node + 1, mid + 1, dr);
        aint[node] = max(aint[2 * node], aint[2 * node + 1]);
    }
}

//O(logN)
void update(int node, int st, int dr, int pos, int val) {
    if(st == dr) {
        aint[node] = val;
    } else {
        int mid = (st + dr) / 2;
        //[st, mid]
        if(pos <= mid) {
            update(2 * node, st, mid, pos, val);
        } else {
            update(2 * node + 1, mid + 1, dr, pos, val);
        }
        //[mid + 1, dr]
        aint[node] = max(aint[2 * node], aint[2 * node + 1]);
    }
}

//O(log N)
int query(int node, int st, int dr, int x, int y) {
    if(x <= st && dr <= y) {//[x ... st ... dr ... y]
        return aint[node];
    } else {
        int mid = (st + dr) / 2;
        //[st, mid]
        int L = 0;
        if(x <= mid) {
            L = query(2 * node, st, mid, x, y);
        }
        //[mid + 1, dr]
        int R = 0;
        if(mid + 1 <= y) {
            R = query(2 * node + 1, mid + 1, dr, x, y);
        }
        return max(L, R);
    }
}

int main() {
    ifstream cin("arbint.in");
    ofstream cout("arbint.out");
	int n, q;
    cin >> n >> q;
    for(int i = 1; i <= n; i++) {
        cin >> v[i];
    }
    build(1, 1, n);
    while(q--) {
        int op, x, y;
        cin >> op >> x >> y;
        if(op == 0) {
            cout << query(1, 1, n, x, y) << '\n';
        } else {
            update(1, 1, n, x, y);
        }
    }
}