Submission #1077446

#	Time	Username	Problem	Language	Result	Execution time	Memory
1077446		vjudge1	Toll (BOI17_toll)	C++17	100 / 100	225 ms	65772 KiB

toll

#include <bits/stdc++.h>

#define endl '\n'

using namespace std;

void FastIO(string name = "")
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    if (name.empty() == 0)
    {
        freopen((name + ".in").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
}

void solve()
{
    int k, n, m, o;

    cin >> k >> n >> m >> o;

    vector<vector<pair<int, int>>> nei(n);

    for (int i = 1; i <= m; i++)
    {
        int a, b, t;
        cin >> a >> b >> t;
        nei[a].push_back({b, t});
    }

    int lg = log2(n);
    const long long inf = 1e11;

    vector table(n, vector(lg + 1, vector(5, inf)));

    for (int i = 0; i < n; i++)
    {
        for (auto &[to, toll] : nei[i])
        {
            table[i][0][to % k] = toll;
        }
    }

    for (int bit = 1; bit <= lg; bit++)
    {
        for (int i = 0; i < n; i++)
        {
            int jump = (1 << (bit - 1));

            int ind = (i / k + jump ) * k ; 
            for (int rem = 0; rem < k; rem++)
            {
                if (ind >= n)
                    break;

                for (int j = 0; j < k; j++)
                    table[i][bit][j] = min(
                    table[i][bit-1][rem]+table[ind][bit - 1][j],
                        table[i][bit][j]);
                ind++;
            }
        }
    }
    
    for (int q = 1; q <= o; q++)
    {
        int a, b;
        cin >> a >> b;

        if (a == b)
        {
            cout << 0 << endl;
        }
        else if (b/k <= a/k)
        {
            cout << -1 << endl;
        }
        else
        {
            int length = (b / k) - (a / k);

            vector<pair<int, long long>> node{{a, 0}};

            for (int bit = 0; bit <= lg; bit++)
                if (length >> bit & 1)
                {
                    map<int, long long> dis;
                    for (auto &[at, d] : node)
                    {
                        int ind = (at / k + (1<<bit) ) * k ;
                        for (int re = 0; re < k; re++)
                        {
                            if (dis.count(ind))
                                dis[ind] = min(dis[ind], d + table[at][bit][re]);
                            else
                                dis[ind] = d + table[at][bit][re];
                            ind++;
                        }
                    }
                    node.clear();

                    for (auto &e : dis)
                        node.push_back(e);
                }

            long long ans = 2e13;
            for (auto &[at, ds] : node)
                if (at == b)
                {
                    ans = ds;
                }

            cout << (ans >= (int)1e9 ? -1 : ans) << endl;
        }
    }
}
int main()
{
    FastIO("");

    int t = 1;
    //cin >> t;

    for (int i = 0; i < t; i++)
    {
        solve();
    }
}

Compilation message (stderr)

toll.cpp: In function 'void FastIO(std::string)':
toll.cpp:14:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |         freopen((name + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
toll.cpp:15:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |         freopen((name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 10 / 10
• Subtask 3: 8 / 8
• Subtask 4: 31 / 31
• Subtask 5: 44 / 44