Cod sursa(job #986950)

Utilizator stefanfStefan Fulger stefanf Data 19 august 2013 20:41:35
Problema Arbori de intervale Scor 0
Compilator c Status done
Runda Arhiva educationala Marime 1.3 kb
#include<stdio.h>
#include<stdlib.h>

int *arb;

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

void update(int nod, int st, int dr, int pos, int val) {
    if (st == dr) {
        arb[nod] = val;
        return;
    }

    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];
    else {
        int result; 
        int mij = (st + dr) / 2;
        if (a <= mij)
            result = query(nod * 2, st, mij, a, b);
        else if (b > mij)
            result = query(nod * 2 + 1, mij + 1, dr, a, b);

        return result;
    }
}

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

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

    i = 1;
    while (i < n)
        i <<= 1;
    arb = malloc(i * sizeof(int));

    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;
}