Submission #959496

#	Time	Username	Problem	Language	Result	Execution time	Memory
959496		OIaspirant2307	Olympic Bus (JOI20_ho_t4)	C++17	0 / 100	1080 ms	3164 KiB

ho_t4

#include <iostream>
#include <vector>
#include <utility>
using namespace std;
#define int long long
#define pi pair<int, int>
const int N = 203;
int inf = 1e15;
int dp[N][N];
vector<vector<int>> arr(N, vector<int>(N, inf));
vector<vector<int>> cost(N, vector<int>(N, -1));
vector<vector<int>> arr2(N, vector<int>(N, inf));
vector<vector<bool>> done(N, vector<bool>(N, 0));
int n, m;

int floyd()
{
    for (int i = 0; i <= n; i++)
    {
        for (int j = 0; j <= n; j++)
        {
            dp[i][j] = arr[i][j];
        }
    }
    for (int k = 1; k <= n; k++)
    {
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++)
            {
                dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j]);
            }
        }
    }
    return min(dp[1][n] + dp[n][1], inf);
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    cin >> n >> m;
    for (int i = 0; i <= n; i++)
    {
        arr[i][i] = 0;
    }
    vector<pi> v(m);
    for (int i = 0; i < m; i++)
    {
        int a, b, c, d;
        cin >> a >> b >> c >> d;
        if (c < arr[a][b])
        {
            arr2[a][b] = arr[a][b];
            arr[a][b] = c;
        }
        cost[a][b] = d;
        v[i] = {a, b};
    }
    int ans = floyd();
    for (auto p : v)
    {
        int i = p.first;
        int j = p.second;
        if (done[i][j])
            continue;
        done[i][j] = true;
        int x = arr[j][i];
        arr[j][i] = min(arr[j][i], arr[i][j]);
        arr[i][j] = arr2[i][j];
        ans = min(ans, floyd() + cost[i][j]);
        arr[i][j] = arr[j][i];
        arr[j][i] = x;
    }

    cout << (ans == inf ? -1 : ans) << '\n';
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63