Submission #1118515

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118515		gdragon	Toll (BOI17_toll)	C++17	56 / 100	3042 ms	22704 KiB

toll

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 1e5 + 5;
const int M = 1e6 + 5;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
struct DSU {
    int n;
    vector<int> par;
    DSU(int _n = 0) {
        n = _n;
        par.assign(n + 2, -1);
    }
    int root(int v) {
        return par[v] < 0 ? v : (par[v] = root(par[v]));
    } 
    bool join(int x, int y) {
        x = root(x);
        y = root(y);
        if (x == y) return false;
        if (par[y] < par[x]) swap(x, y);
        par[x] += par[y];
        par[y] = x;
        return true;
    }
} dsu;
struct Edge {
    int u, v, c;
    Edge(int _u = 0, int _v = 0, int _c = 0) {
        u = _u; v = _v; c = _c;
    }
} e[M];
vector<ii> adj[N];
int n, K, m, q;
void read() {
    cin >> K >> n >> m >> q;
    dsu = DSU(n);
    for(int i = 1; i <= m; i++) {
        int u, v, c; cin >> u >> v >> c;
        assert(v - u < 2 * K);
        adj[u].push_back({v, c});
        dsu.join(u, v);
        if (K == 1) assert(v == u + 1);
        e[i] = Edge(u, v, c);  
    }
}
long long dfs(int s, int t) {
    vector<long long> d(n + 1, INF);
    d[s] = 0;
    priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> heap;
    heap.push({0, s});
    while(!heap.empty()) {
        auto tmp = heap.top(); heap.pop();
        long long du = tmp.fi;
        int u = tmp.se;
        if (du != d[u]) continue;
        if (u == t) break;
        for(auto [v, c]: adj[u]) if (minimize(d[v], du + c)) {
            heap.push({d[v], v});
        }
    }
    return d[t] == INF ? -1 : d[t];
}
long long dp[N];
long long backtrack(int u, int t) {
    if (u == t) return 0;
    if (u / K >= t / K) return INF;
    long long &res = dp[u];
    if (res != -1) return res;
    res = INF;
    for(auto [v, c]: adj[u]) {
        minimize(res, backtrack(v, t) + c);
    } 
    return res;
}
void solve() {
    vector<long long> d(n + 2, 0);
    if (K == 1) {
        for(int i = 1; i <= m; i++) d[e[i].v] = e[i].c;
        for(int i = 1; i <= n; i++) d[i] += d[i - 1];
    }
    vector<long long> d0(n + 1, INF);
    d0[0] = 0;
    priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> heap;
    heap.push({0, 0});
    while(!heap.empty()) {
        auto tmp = heap.top(); heap.pop();
        long long du = tmp.fi;
        int u = tmp.se;
        if (du != d0[u]) continue;
        for(auto [v, c]: adj[u]) if (minimize(d0[v], du + c)) {
            heap.push({d0[v], v});
        }
    }
    while(q--) {
        int u, v; cin >> u >> v;
        if (u == v) {
            cout << 0 << endl;
            continue;
        }
        if (u > v || u/K == v/K || dsu.root(u) != dsu.root(v)) {
            cout << -1 << endl;
            continue;
        }
        if (K == 1) {
            cout << d[v] - d[u] << endl;
            continue;
        }
        if (u == 0) {
            cout << (d0[v] == INF ? -1 : d0[v]) << endl;
            continue;
        }
        for(int i = 0; i < n; i++) dp[i] = -1;
        long long ans = backtrack(u, v);
        cout << (ans == INF ? -1 : ans) << endl;
        // cout << dfs(u, v) << endl;
    }
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

// rmq - rmq2d
// hash
// fw - fw2d
// segtree

Compilation message (stderr)

toll.cpp: In function 'int main()':
toll.cpp:137:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  137 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
toll.cpp:138:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  138 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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