Submission #838483

#	Time	Username	Problem	Language	Result	Execution time	Memory
838483		green_gold_dog	Olympic Bus (JOI20_ho_t4)	C++17	100 / 100	799 ms	5660 KiB

ho_t4

//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,abm,popcnt,mmx")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef double db;
typedef long double ldb;
typedef complex<double> cd;

constexpr ll INF64 = 1'000'000'000'000'000'000, INF32 = 2'000'000'000, MOD = 1'000'000'007;
constexpr db PI = acos(-1);
constexpr bool IS_FILE = false, IS_TEST_CASES = false;

random_device rd;
mt19937 rnd32(rd());
mt19937_64 rnd64(rd());

template<typename T>
bool assign_max(T& a, T b) {
        if (b > a) {
                a = b;
                return true;
        }
        return false;
}

template<typename T>
bool assign_min(T& a, T b) {
        if (b < a) {
                a = b;
                return true;
        }
        return false;
}

template<typename T>
T square(T a) {
        return a * a;
}

template<>
struct std::hash<pair<ll, ll>> {
        ll operator() (pair<ll, ll> p) const {
                return ((__int128)p.first * MOD + p.second) % INF64;
        }
};

pair<vector<ll>, vector<ll>> get_dist(ll v, vector<tuple<ll, ll, ll, ll>>& arr, ll n) {
        vector<vector<ll>> to(n, vector<ll>(n, INF64));
        for (auto[a, b, c, d] : arr) {
                assign_min(to[a][b], c);
        }
        vector<ll> dist(n, INF64);
        vector<ll> p(n, -1);
        dist[v] = 0;
        priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> q;
        q.push(make_pair(0ll, v));
        while (!q.empty()) {
                auto[d, x] = q.top();
                q.pop();
                if (d != dist[x]) {
                        continue;
                }
                for (ll i = 0; i < n; i++) {
                        if (assign_min(dist[i], d + to[x][i])) {
                                p[i] = x;
                                q.push(make_pair(dist[i], i));
                        }
                }
        }
        return make_pair(dist, p);
}

vector<ll> get_way(ll v, vector<ll>& dist, vector<ll>& p, vector<vector<ll>>& rarr, vector<tuple<ll, ll, ll, ll>>& arr) {
        ll now = v;
        ll nd = dist[v];
        vector<ll> ans;
        if (p[now] == -1) {
                return ans;
        }
        while (p[now] != -1) {
                for (auto i : rarr[now]) {
                        if (nd == get<2>(arr[i]) + dist[get<0>(arr[i])] && get<0>(arr[i]) == p[now]) {
                                ans.push_back(i);
                                nd -= get<2>(arr[i]);
                                now = get<0>(arr[i]);
                                break;
                        }
                }
        }
        reverse(ans.begin(), ans.end());
        return ans;
}

void solve() {
        ll n, m;
        cin >> n >> m;
        vector<tuple<ll, ll, ll, ll>> arr(m);
        for (auto&[a, b, c, d] : arr) {
                cin >> a >> b >> c >> d;
                a--;
                b--;
        }
        vector<vector<ll>> dists(n), ps(n);
        for (ll i = 0; i < n; i++) {
                auto[d, p] = get_dist(i, arr, n);
                dists[i] = d;
                ps[i] = p;
        }
        vector<vector<ll>> rarr(n);
        for (ll i = 0; i < m; i++) {
                rarr[get<1>(arr[i])].push_back(i);
        }
        vector<ll> w0n = get_way(n - 1, dists[0], ps[0], rarr, arr), wn0 = get_way(0, dists[n - 1], ps[n - 1], rarr, arr);
        ll ans = dists[0][n - 1] + dists[n - 1][0];
        vector<ll> d0r(m, -1), dnr(m, -1);
        for (auto i : w0n) {
                swap(get<0>(arr[i]), get<1>(arr[i]));
                d0r[i] = get_dist(0, arr, n).first[n - 1];
                swap(get<0>(arr[i]), get<1>(arr[i]));
        }
        for (ll i = 0; i < m; i++) {
                if (d0r[i] == -1) {
                        d0r[i] = min(dists[0][n - 1], dists[0][get<1>(arr[i])] + get<2>(arr[i]) + dists[get<0>(arr[i])][n - 1]);
                }
        }
        for (auto i : wn0) {
                swap(get<0>(arr[i]), get<1>(arr[i]));
                dnr[i] = get_dist(n - 1, arr, n).first[0];
                swap(get<0>(arr[i]), get<1>(arr[i]));
        }
        for (ll i = 0; i < m; i++) {
                if (dnr[i] == -1) {
                        dnr[i] = min(dists[n - 1][0], dists[n - 1][get<1>(arr[i])] + get<2>(arr[i]) + dists[get<0>(arr[i])][0]);
                }
        }
        for (ll i = 0; i < m; i++) {
                assign_min(ans, d0r[i] + dnr[i] + get<3>(arr[i]));
        }
        cout << (ans >= INF64 ? -1 : ans) << '\n';
}

int main() {
        if (IS_FILE) {
                freopen("", "r", stdin);
                freopen("", "w", stdout);
        }
        ios_base::sync_with_stdio(false);
        cin.tie(0);
        cout.tie(0);
        ll t = 1;
        if (IS_TEST_CASES) {
                cin >> t;
        }
        for (ll i = 0; i < t; i++) {
                solve();
        }
}

Compilation message (stderr)

ho_t4.cpp: In function 'int main()':
ho_t4.cpp:147:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  147 |                 freopen("", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~
ho_t4.cpp:148:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  148 |                 freopen("", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~

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