Submission #1028548

#	Time	Username	Problem	Language	Result	Execution time	Memory
1028548		GrandTiger1729	Flooding Wall (BOI24_wall)	C++17	48 / 100	1515 ms	10244 KiB

Main

#include <bits/stdc++.h>
using namespace std;

const int N = 5e5 + 10, C = 1010, MOD = 1e9 + 7;
long long pw2[N];
void precalc()
{
    pw2[0] = 1;
    for (int i = 1; i < N; i++)
    {
        pw2[i] = pw2[i - 1] * 2 % MOD;
    }
}
int main()
{
    precalc();
    cin.tie(0)->sync_with_stdio(0);
    int n;
    cin >> n;
    vector<int> a(n), b(n);
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
    }
    for (int i = 0; i < n; i++)
    {
        cin >> b[i];
        if (a[i] > b[i])
        {
            swap(a[i], b[i]);
        }
    }
    long long ans = 0;
    for (int i = 0; i < n; i++)
    {
        (ans += pw2[n - 1] * (b[i] - a[i] + (C - b[i]) * 2ll)) %= MOD;
    }
    vector<long long> coef(C, 1);
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < a[i]; j++)
        {
            coef[j] = 0;
        }
        for (int j = b[i]; j < C; j++)
        {
            (coef[j] *= 2) %= MOD;
        }
        long long tot = accumulate(coef.begin(), coef.end(), 0ll) % MOD;
        (ans += MOD - pw2[n - i - 1] * tot % MOD) %= MOD;
    }
    fill(coef.begin(), coef.end(), 1ll);
    for (int i = n - 1; i >= 0; i--)
    {
        for (int j = 0; j < a[i]; j++)
        {
            coef[j] = 0;
        }
        for (int j = b[i]; j < C; j++)
        {
            (coef[j] *= 2) %= MOD;
        }
        long long tot = accumulate(coef.begin(), coef.end(), 0ll) % MOD;
        (ans += MOD - pw2[i] * tot % MOD) %= MOD;
    }
    long long tot = accumulate(coef.begin(), coef.end(), 0ll) % MOD;
    (ans += n * tot % MOD) %= MOD;
    cout << ans << '\n';
    return 0;
}

• Subtask 1: 0 / 8
• Subtask 2: 17 / 17
• Subtask 3: 19 / 19
• Subtask 4: 0 / 14
• Subtask 5: 12 / 12
• Subtask 6: 0 / 30