Hi,

I have been trying to solve GSS1 on Spoj and its giving me segmentation fault. I am not able to figure out whats the problem. Below is my code, please see if you can figure out whats the problem.

http://www.spoj.com/problems/GSS1/

#include <iostream>
#include <algorithm>
#define MAX 500005
using namespace std;

struct data {
    long long sum, prefix_sum, suffix_sum, ans;
    data(long long val) {
        sum = val;
        prefix_sum = suffix_sum = ans = max(0LL, val);
    }
    data(long long a, long long b, long long c, long long d) : sum(a), prefix_sum(b), suffix_sum(c), ans(d) {}
    data(){}
};

data tree[4 * MAX];
long long arr[MAX];

data combine(data l, data r)
{
    data res;
    res.sum = l.sum + r.sum;
    res.prefix_sum = max(l.prefix_sum, l.sum + r.prefix_sum);
    res.suffix_sum = max(r.suffix_sum, r.sum + l.suffix_sum);
    res.ans = max(max(l.ans, r.ans), l.suffix_sum + r.prefix_sum);

    return res;
}

void build(long long node, long long tl, long long tr)
{
    if (tl > tr) return;

    if (tl == tr)
        tree[node] = data(arr[tl]);
    else {
        long long tm = (tl + tr) / 2;
        build(node * 2, tl, tm);
        build((node * 2) + 1, tm + 1, tr);

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

data query(long long node, long long tl, long long tr, long long l, long long r)
{
    if (tl > tr || r < tl || l > tr) return data(0, -1e9, -1e9, -1e9);

    if (tl <= l && r >= tr)
        return tree[node];

    long long tm = (tl + tr) / 2;
    data n1 = query(node * 2, tl, tm, l, r);
    data n2 = query((node * 2) + 1, tm + 1, tr, l, r);

    return combine(n1, n2);
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    long long n;
    cin >> n;
    for (long long i = 0; i < n; i++)
        cin >> arr[i];

    build(1, 0, n - 1);
    long long m;
    cin >> m;
    while (m--) {
        long long x, y;
        cin >> x >> y;
        cout << query(1, 0, n - 1, x - 1, y - 1).ans << "\n";
    }

    return 0;
}