제출 #1266202

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1266202		nguyn	Olympic Bus (JOI20_ho_t4)	C++20	21 / 100	23 ms	1864 KiB

ho_t4

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

#define ll long long
#define F first
#define S second
#define pb push_back
#define pii pair<int, int>

const ll inf = 1e18;

struct Edge {
    int u, v, c, d;
} edges[50005];

vector<int> g[205];
int n, m;
ll d[205][205];
ll d0[205];
int used[50005];

ll dijkstra(int s, int type) {
    vector<int> vis(n + 3, 0);
    vector<int> trace(n + 3, 0);
    for (int i = 1; i <= n; i++) {
        d0[i] = inf;
    }
    d0[s] = 0;
    for (int i = 1; i <= n; i++) {
        int u = 0;
        for (int j = 1; j <= n; j++) {
            if (!vis[j]) {
                if (u == 0 || d0[u] > d0[j]) u = j;
            }
        }
        vis[u] = 1;
        for (int id : g[u]) {
            if (d0[u] + edges[id].c < d0[edges[id].v]) {
                d0[edges[id].v] = d0[u] + edges[id].c;
                trace[edges[id].v] = id;
            }
        }
    }
    int u;
    if (s == 1) u = n;
    if (s == n) u = 1;
    if (d0[u] == inf) return inf;
    if (type == 1) {
        while(u != s) {
            used[trace[u]] = 1;
            u = edges[trace[u]].u;
        }
    }
    return d0[u];
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            if (i == j) continue;
            d[i][j] = inf;
        }
    }
    for (int i = 1; i <= m; i++) {
        int u, v, c, dd;
        cin >> u >> v >> c >> dd;
        g[u].pb(i);
        edges[i] = {u, v, c, dd};
        d[u][v] = c;
    }
    for (int k = 1; k <= n; k++) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
            }
        }
    }
    ll res = d[1][n] + d[n][1];
    dijkstra(1, 1);
    dijkstra(n, 1);
    for (int i = 1; i <= m; i++) {
        int u = edges[i].u;
        int v = edges[i].v;
        int c = edges[i].c;
        int dd = edges[i].d;
        ll tmp = min(d[1][n], d[1][v] + c + d[u][n]) + min(d[n][1], d[n][v] + c + d[u][1]) + dd;
//        if (!used[i]) {
//            res = min(res, tmp);
//        }
        if (tmp < res) {
            g[u].erase(find(g[u].begin(), g[u].end(), i));
            swap(edges[i].u, edges[i].v);
            g[v].pb(i);
            res = min(res, dijkstra(1, 0) + dijkstra(n, 0) + dd);
            g[v].pop_back();
            swap(edges[i].u, edges[i].v);
            g[u].pb(i);
        }
    }
    if (res >= inf) {
        cout << -1;
    }
    else cout << res;
}

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