Получение из множества сумму равную нулю

#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <vector>
#include <stdio.h>
#include <cmath>
#include <math.h>
#include <queue>
#include <stack>
#include <climits>
#include <deque>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;

#define mh() make_heap()
#define poph() pop_heap()
#define pushh() push_heap()
#define sor(n) n.begin(), n.end()
#define rsor(n) n.rbegin(), n.rend()
#define mp make_pair
#define files freopen("input.txt", "rt", stdin); freopen("output.txt", "wt", stdout)
#define p(T) pair<T,T>
#define znac(l) abs(l)/l
const ll ok = ll(1e9 + 7);

int main()
{
    //files;
    ll n;
    cin >> n;
    ll arr[2001];
    ll sum = 0;
    for (int i = 0; i < n; i++)
    {
        cin >> arr[i];
        sum += arr[i];
    }
    vector<ll>way(sum + 1);
    vector<ll>pos(sum + 1);
    if (sum == 0)
    {
        for (int i = 0; i < n; i++)
        {
            cout << "+";
        }
        return 0;
    }
    for (int i = 0; i < sum+1; ++i)
        way[i] = 0;

    way[0] = 1;

    for (int i = 0; i < n; ++i)
        for (ll j = sum; j > 0; --j)
        {
            if (arr[i] != 0)
                if (j >= arr[i] && way[j - arr[i]] != 0&&way[j]==0)
                {
                    way[j] = arr[i];
                    pos[j] = i;
                }
        }

    ll j = sum / 2;
    while (j != 0)
    {
        arr[pos[j]] = -arr[pos[j]];
        j -= way[j];
    }
    string h = "";
    for (int i = 0; i < n; i++)
    {
        if (arr[i] < 0)
            h += "-";
        else
        {
            h += "+";
        }
    }
    cout << h;
    return 0;
}