Submission #1006938

#	Time	Username	Problem	Language	Result	Execution time	Memory
1006938		overwatch9	Toll (BOI17_toll)	C++17	7 / 100	21 ms	5704 KiB

toll

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn = 50001;
vector <pair <int, int>> adj[maxn];
ll dis[maxn];
bool processed[maxn];
queue <int> modified;
int pos[maxn];
vector <vector <ll>> pfx;
int id[maxn];
ll dijkstra(int st, int ed) {
    dis[st] = 0;
    priority_queue <pair <ll, int>> pq;
    pq.push({0, st});
    pos[st] = 0;
    while (!pq.empty()) {
        int s = pq.top().second;
        pq.pop();
        if (processed[s])
            continue;
        processed[s] = true;
        modified.push(s);
        id[s] = (int)pfx.size()-1;
        pfx.back().push_back(dis[s]);
        for (auto i : adj[s]) {
            if (dis[i.first] > dis[s] + i.second) {
                dis[i.first] = dis[s] + i.second;
                pq.push({-dis[i.first], i.first});
                pos[i.first] = pos[s] + 1;
            }
        }
    }
    ll ans = 0;
    if (dis[ed] == 1e18) {
        dis[ed] = -1;
        modified.push(ed);
    }
    ans = dis[ed];
    return ans;
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int K, N, M, O;
    cin >> K >> N >> M >> O;
    for (int i = 0; i < M; i++) {
        int a, b, t;
        cin >> a >> b >> t;
        adj[a].push_back({b, t});
    }
    fill(dis, dis + N + 1, 1e18);
    pfx.emplace_back();
    for (int i = 0; i < N; i++) {
        if (!adj[i].empty() && !processed[i]) {
            pfx.emplace_back();
            dijkstra(i, i);
        }
    }
    while (O--) {
        int a, b;
        cin >> a >> b;
        if (id[a] != id[b] || min(id[a], id[b]) == 0)
            cout << -1 << '\n';
        else
            cout << pfx[id[a]][pos[b]] - pfx[id[a]][pos[a]] << '\n';
    }
}

• Subtask 1: 7 / 7
• Subtask 2: 0 / 10
• Subtask 3: 0 / 8
• Subtask 4: 0 / 31
• Subtask 5: 0 / 44