Submission #1287864

#	Time	Username	Problem	Language	Result	Execution time	Memory
1287864		nanaseyuzuki	Olympic Bus (JOI20_ho_t4)	C++20	0 / 100	1095 ms	3072 KiB

ho_t4

#include <bits/stdc++.h>
// Author: Ilove._.Ghibli0369
#define fi first
#define se second
#define pii pair<int,int>
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;

const int mn = 2e2 + 5;
const int mod = 1000000007LL, inf = 1e15;

int n, m, kc[mn][mn], imp[mn], d1[mn], dn[mn], par[mn];

struct Egde{
    int u, v, c, w;
} e[500005];

vector <int> a[mn];

void dijkstra(int u, int d[]){
    for(int i = 1; i <= n; i++){
        d[i] = inf;
        par[i] = 0;
    }
    d[u] = 0;
    priority_queue <pii, vector <pii>, greater<pii>> pq;
    pq.push({d[u], u});

    while(pq.size()){
        auto [c, u] = pq.top();
        pq.pop();
        if(c > d[u]) continue;
        for(auto i : a[u]){
            if(d[e[i].v] > d[u] + e[i].c){
                d[e[i].v] = d[u] + e[i].c;
                par[e[i].v] = i;
                pq.push({d[e[i].v], e[i].v});
            }
        }
    }

}   

void solve(){
    cin >> n >> m;
    fill(&kc[0][0], &kc[0][0] + mn * mn, inf);
    for(int i = 1; i <= n; i++) kc[i][i] = 0;
    for(int i = 1; i <= m; i++){
        int u, v, c, w; cin >> u >> v >> c >> w;
        a[u].push_back(i);
        e[i] = {u, v, c, w};
        kc[u][v] = min(kc[u][v], c);
    }

    dijkstra(1, d1);
    int cur = n;
    while(cur && par[cur]){
        imp[par[cur]] = 1;
        cur = e[par[cur]].u;
    }

    dijkstra(n, dn);
    cur = 1;
    while(cur && par[cur]){
        imp[par[cur]] = 1;
        cur = e[par[cur]].u;
    }
    
    for(int k = 1; k <= n; k++){
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= n; j++){
                kc[i][j] = min(kc[i][j], kc[i][k] + kc[k][j]);
            }
        }
    }
    
    int res = d1[n] + dn[1];

    for(int i = 1; i <= m; i++){
        auto [u, v, c, w] = e[i];
        if(!imp[i]){
            res = min(res, min(kc[1][n], kc[1][v] + c + kc[u][n])
                        + min(kc[n][1], kc[n][v] + c + kc[u][1]) + w);
        }
        else{
            a[u].erase(find(all(a[u]), i));
            swap(e[i].u, e[i].v);
            a[v].push_back(i);

            dijkstra(1, d1); dijkstra(n, dn);
            res = min(d1[n] + dn[1] + w, res);

            a[v].erase(find(all(a[v]), i));
            swap(e[i].u, e[i].v);
            a[u].push_back(i);
        }
    }
    if(res > inf) res = -1;
    cout << res << '\n';
}
// Waifu of the day: Persia Juliet
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    if(fopen("multship.inp", "r")){
        freopen("multship.inp", "r", stdin);
        freopen("multship.out", "w", stdout);
    }
    int t = 1;
    // cin >> t;
    while(t--) solve();
}

Compilation message (stderr)

ho_t4.cpp: In function 'int main()':
ho_t4.cpp:108:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |         freopen("multship.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
ho_t4.cpp:109:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  109 |         freopen("multship.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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