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Submission #958478

# Submission time Handle Problem Language Result Execution time Memory
958478 2024-04-05T21:12:49 Z BhavayGoyal Olympic Bus (JOI20_ho_t4) C++14
5 / 100
 1000 ms 5892 KB 
#include <bits/stdc++.h>
using namespace std;

#define int long long
#define vi vector<int>
#define vii vector<vector<int>>
#define pii pair<int, int>
#define pb push_back
#define f first
#define s second
#define endl "\n"

const int linf = 1e15;

// -------------------------------------------------- Main Code --------------------------------------------------

const int N = 201, M = 50001;
int n, m;
set<pii> g[N];
vii edges;
map<pair<int, int>, bool> isShort;

void dijkstra(int source) {
    priority_queue<pii, vector<pii>, greater<>> q;
    vi vis(n+1, 0), dis(n+1, linf), par(n+1);
    q.push({0, source});
    dis[source] = 0;
    while (!q.empty()) {
        pii f = q.top(); q.pop();
        int src = f.s;
        if (vis[src]) continue;
        vis[src] = true;

        for (auto child : g[src]) {
            int ch = child.f, wt = child.s;
            if (dis[ch] > dis[src] + wt) {
                par[ch] = src;
                isShort[{par[ch], ch}] = true;
                dis[ch] = dis[src] + wt;
                q.push({dis[ch], ch});
            }
        }
    }

    // int x = (source==1?n:1);
    // while (par[x]) {
    //     isShort[{par[x], x}] = true;
    //     x = par[x];
    // }
}

int get_dist(int s, int t) {
    vi D(n+1, linf);
    priority_queue<pii, vector<pii>, greater<pii>> pq;
    D[s] = 0;
    pq.emplace(0, s);
    while (pq.size()) {
        pii temp = pq.top(); int x = temp.f, u = temp.s;
        pq.pop();
        if (D[u] == x) {
            for (pii child : g[u]) {
                int v = child.f, wt = child.s;
                if (D[v] > x + wt) {
                    pq.emplace(D[v] = x + wt, v);
                }
            }
        }
    }
    return D[t];
}


void sol() {
    cin >> n >> m;
    vii dist(n+1, vi(n+1, linf));
    for (int i = 1; i <= n; i++) dist[i][i] = 0;

    for (int i = 1; i <= m; i++) {
        int a, b, c, d; cin >> a >> b >> c >> d;
        dist[a][b] = min(dist[a][b], c);
        g[a].insert({b, c});
        edges.pb({a, b, c, d});
    }

    dijkstra(1);
    dijkstra(n);
    
    for (int k = 1; k <= n; ++k) {
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= n; ++j) {
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
            }
        }
    }

    int ans = min(linf, dist[1][n] + dist[n][1]);

    for (auto i : edges) {
        int a = i[0], b = i[1], c = i[2], d = i[3];
        // if (isShort[{a, b}]) {
            g[a].erase({b, c});
            g[b].insert({a, c});
            ans = min(ans, get_dist(1, n) + get_dist(n, 1) + d);
            g[b].erase({a, c});
            g[a].insert({b, c});
        // }
        // else {
        //     int A = min(dist[1][n], dist[1][b] + c + dist[a][n]);
        //     int B = min(dist[n][1], dist[n][b] + c + dist[a][1]);
        //     if (A < linf && B < linf) {
        //         ans = min(ans, A + B + d);
        //     }
        // }
    }

    cout << (ans==linf?-1:ans) << endl;
}

signed main () {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int t = 1;
    // cin >> t; 
    while (t--) {
        sol();
    }
    return 0;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 31 ms 860 KB Output is correct
2 Correct 7 ms 604 KB Output is correct
3 Correct 50 ms 860 KB Output is correct
4 Correct 52 ms 944 KB Output is correct
5 Correct 17 ms 604 KB Output is correct
6 Correct 7 ms 604 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 13 ms 604 KB Output is correct
10 Correct 70 ms 860 KB Output is correct
11 Correct 69 ms 856 KB Output is correct
12 Correct 72 ms 856 KB Output is correct
13 Correct 29 ms 860 KB Output is correct
14 Correct 31 ms 860 KB Output is correct
15 Correct 28 ms 856 KB Output is correct
16 Correct 32 ms 860 KB Output is correct

Subtask #2
0 / 11.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1046 ms 5892 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 30 ms 856 KB Output is correct
2 Correct 8 ms 604 KB Output is correct
3 Execution timed out 1068 ms 5040 KB Time limit exceeded
4 Halted 0 ms 0 KB -

Subtask #4
0 / 63.0

# Verdict Execution time Memory Grader output
1 Correct 31 ms 860 KB Output is correct
2 Correct 7 ms 604 KB Output is correct
3 Correct 50 ms 860 KB Output is correct
4 Correct 52 ms 944 KB Output is correct
5 Correct 17 ms 604 KB Output is correct
6 Correct 7 ms 604 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 13 ms 604 KB Output is correct
10 Correct 70 ms 860 KB Output is correct
11 Correct 69 ms 856 KB Output is correct
12 Correct 72 ms 856 KB Output is correct
13 Correct 29 ms 860 KB Output is correct
14 Correct 31 ms 860 KB Output is correct
15 Correct 28 ms 856 KB Output is correct
16 Correct 32 ms 860 KB Output is correct
17 Execution timed out 1046 ms 5892 KB Time limit exceeded
18 Halted 0 ms 0 KB -