Cod sursa(job #987035)

Utilizator stefanfStefan Fulger stefanf Data 19 august 2013 22:27:39
Problema Arbori de intervale Scor 50
Compilator c Status done
Runda Arhiva educationala Marime 1.24 kb
#include<stdio.h>
#include<stdlib.h>

int arb[1<<19];

int max(int a, int b) {
    return (a > b) ? a : b;
}

void update(int nod, int st, int dr, int pos, int val) {
    if (st == dr) {
        arb[nod] = val;
        return;
    } else {
        int mij = (st + dr) / 2;
        if (pos <= mij)
            update(nod * 2, st, mij, pos, val);
        else
            update(nod * 2 + 1, mij + 1, dr, pos, val);
    
        arb[nod] = max(arb[nod*2], arb[nod * 2 + 1]);
    }
}

int query(int nod, int st, int dr, int a, int b) {
    if (a <= st && dr <= b)
        return arb[nod];

    int mij = (st + dr) / 2;
    int ml, mr;
    ml = -1;
    mr = -1;

    if (a <= mij)
        ml = query(nod * 2, st, mij, a, b);
    if (b > mij)
        mr = query(nod * 2 + 1, mij + 1, dr, a, b);

    return max(ml, mr);
}

int main() {
    freopen("arbint.in", "r", stdin);
    freopen("arbint.out", "w", stdout);

    int n, m, x, i;
    scanf("%d%d", &n, &m);

    for (i = 1; i <= n; i++) {
       scanf("%d", &x);
       update(1, 1, n, i, x);
    }

    int a, b;
    for (i = 0; i < m; i++) {
        scanf("%d%d%d", &x, &a, &b);
        if (x == 0)
            printf("%d\n", query(1, 1, n, a, b));
        else
            update(1, 1, n, a, b);
    }

    return 0;
}