Submission #55020237

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define mp make_pair
#define all(x) x.begin(), x.end()
#define x first
#define y second

const int mod = 1e9 + 7;


void solve() {

    int n;
    cin >> n;
    vector<int> A(n);
    for (auto& i : A) cin >> i;

    vector<ll> dp(2020), init(2020);
    int b = 1000;
    init[b] = 1;
    for (int i = 0; i < n; i++) {
        ll v = A[i];
        if (v > 0) {
            for (int j = b * 2; j >= v; j--) {
                if (j == b + v) {
                    init[j] = dp[b] + 1;
                    //(dp[j] += dp[j - v]) %= mod;
                }
                else (dp[j] += dp[j - v] + init[j-v]) %= mod;
            }
        }
        else if (v < 0) {
            for (int j = 0; j - v <= b * 2 ; j++) {
                if (j == b + v) {
                    init[j] = dp[b] + 1;
                   // (dp[j] += dp[j - v]) %= mod;
                }
                else (dp[j] += dp[j - v] + init[j-v]) %= mod;
            }
        }
        else {
            for (int j = 0; j <= b * 2; j++) {
                if (j == b) {}
                else (dp[j] += dp[j + v] + init[j+v]) %= mod;
            }
        }
    }
    ll ans = 0;
    for (auto f : dp) ans = (ans + f) % mod;
    cout << (ans + 1) % mod << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int t = 1;
    // cin >> t;
    while (t--) solve();
}

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