Submission #1180641

#	Time	Username	Problem	Language	Result	Execution time	Memory
1180641		blackslex	Commuter Pass (JOI18_commuter_pass)	C++17	15 / 100	331 ms	20468 KiB

commuter_pass

#include<bits/stdc++.h>

using namespace std;
using ll = long long;
using pii = pair<ll, ll>;

int n, m, s, t, uu, vv, x, y, z;

int main() {
    scanf("%d %d %d %d %d %d", &n, &m, &s, &t, &uu, &vv);
    vector<vector<pii>> v(n + 5, vector<pii>());
    vector<ll> d(n + 5, 1e18), d2(n + 5, 1e18);
    ll ans = 1e18;
    for (int i = 0; i < m; i++) {
        scanf("%d %d %d", &x, &y, &z);
        v[x].emplace_back(y, z);
        v[y].emplace_back(x, z);
    }
    auto dijk = [&] (int st, vector<ll> &dist) {
        priority_queue<pii, vector<pii>, greater<pii>> pq;
        pq.emplace(dist[st] = 0, st);
        while (!pq.empty()) {
            auto [nd, nn] = pq.top(); pq.pop();
            for (auto &[tn, td]: v[nn]) {
                if (dist[tn] > dist[nn] + td) pq.emplace(dist[tn] = dist[nn] + td, tn);
            }
        }
    };
    auto dijk2 = [&] (int st, int ed) {
        priority_queue<pii, vector<pii>, greater<pii>> pq;
        vector<ll> dist(n + 5, 1e18);
        vector<vector<ll>> dp(2, vector<ll>(n + 5, 1e18));
        pq.emplace(dist[st] = 0, st);
        while (!pq.empty()) {
            auto [nd, nn] = pq.top(); pq.pop();
            for (auto &[tn, td]: v[nn]) {
                ll xx0 = min(dp[0][nn], d[tn]), xx1 = min(dp[1][nn], d2[tn]);
                if (dist[tn] > dist[nn] + td) {
                    dp[0][tn] = xx0;
                    dp[1][tn] = xx1;
                    pq.emplace(dist[tn] = dist[nn] + td, tn);
                } else if (dist[tn] == dist[tn] + td && xx0 + xx1 <= dp[0][tn] + dp[1][tn]) {
                    dp[0][tn] = xx0;
                    dp[1][tn] = xx1;
                }
            }
        }
        ans = min(ans, dp[0][ed] + dp[1][ed]);
    };
    dijk(uu, d);
    dijk(vv, d2);
    ans = min(ans, d[vv]);
    dijk2(s, t);
    dijk2(t, s);
    printf("%lld", ans);
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:10:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 |     scanf("%d %d %d %d %d %d", &n, &m, &s, &t, &uu, &vv);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:15:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |         scanf("%d %d %d", &x, &y, &z);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45