Submission #668583

#	Time	Username	Problem	Language	Result	Execution time	Memory
668583		Do_you_copy	Evacuation plan (IZhO18_plan)	C++17	100 / 100	494 ms	56696 KiB

plan

/*
    I find it wholesome to be alone the greater part of the time.
    To be in company, even with the best, is soon wearisome and dissipating.
    I love to be alone.
    I never found the companion that was so companionable as solitude.
*/
#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define faster ios_base::sync_with_stdio(0); cin.tie(0);

using namespace std;
using ll = long long;
using ld = long double;
using pii = pair <int, int>;
mt19937_64 Rand(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e5 + 1;
//const int Mod = 1e9 + 7;
const ll inf = 0x3f3f3f3f3f3f3f3f;
int n, m, k, q;
vector <pii> adj[maxN];
vector <int> adj1[maxN];
int g[maxN];
ll ans[maxN];
ll d[maxN];
bool on[maxN];
int idx[maxN];
struct TDSU{
    vector <int> lab;
    TDSU(){}
    TDSU(int _n){
        lab.resize(_n, -1);
    }
    inline void resize(int _n){
        lab.resize(_n, -1);
    }
    inline int find_set(int u){
        if (lab[u] < 0) return u;
        return lab[u] = find_set(lab[u]);
    }
    inline bool unite(int u, int v){
        u = find_set(u);
        v = find_set(v);
        if (u == v) return 0;
        if (lab[u] > lab[v]) swap(u, v);
        lab[u] += lab[v];
        lab[v] = u;
        return 1;
    }
};

void Dijkstra(){
    memset(d, 0x3f, sizeof(d));
    priority_queue <pair <ll, int>, vector <pair <ll, int>>, greater <pair <ll, int>>> PQ;
    for (int i = 1; i <= k; ++i){
        PQ.push({0, g[i]});
        d[g[i]] = 0;
    }
    while (!PQ.empty()){
        auto r = PQ.top(); PQ.pop();
        if (d[r.se] != r.fi) continue;
        for (const pii &i: adj[r.se]){
            if (d[r.se] + i.se < d[i.fi]){
                d[i.fi] = d[r.se] + i.se;
                PQ.push({d[i.fi], i.fi});
            }
        }
    }
}
int lift[maxN][20];
ll val[maxN][20];
int depth[maxN];
void dfs(int u, int p){
    depth[u] = depth[p] + 1;
    lift[u][0] = p;
    val[u][0] = d[u];
    for (int i = 1; i < 20; ++i){
        lift[u][i] = lift[lift[u][i - 1]][i - 1];
        val[u][i] = min(val[u][i - 1], val[lift[u][i - 1]][i - 1]);
    }
    for (int i: adj1[u]){
        if (i == p) continue;
        dfs(i, u);
    }
}

int lca(int u, int v){
    if (depth[u] < depth[v]) swap(u, v);
    int k = depth[u] - depth[v];
    ll res = inf;
    while (k){
        int t = __builtin_ctz(k);
        res = min(res, val[u][t]);
        u = lift[u][t];
        k ^= 1 << t;
    }
    if (u == v) return min(res, d[u]);
    for (int i = 19; i >= 0; --i){
        if (lift[u][i] != lift[v][i]){
            res = min(res, val[u][i]);
            res = min(res, val[v][i]);
            u = lift[u][i];
            v = lift[v][i];
        }
    }
    return min(res, min(val[v][1], val[u][1]));
}

void Init(){
    cin >> n >> m;
    TDSU dsu(n + 1);
    for (int i = 1; i <= m; ++i){
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].pb({v, w});
        adj[v].pb({u, w});
    }
    cin >> k;
    for (int i = 1; i <= k; ++i) cin >> g[i];
    Dijkstra();
    iota(idx + 1, idx + n + 1, 1);
    sort(idx + 1, idx + n + 1,[&](const int &i, const int &j){
        return d[i] > d[j];
    });
    for (int i = 1; i <= n; ++i){
        on[idx[i]] = 1;
        for (auto j: adj[idx[i]]){
            if (!on[j.fi]) continue;
            if (dsu.unite(idx[i], j.fi)){
                adj1[idx[i]].pb(j.fi);
                adj1[j.fi].pb(idx[i]);
            }
        }
    }
    dfs(1, 0);
    cin >> q;
    for (int i = 1; i <= q; ++i){
        int s, t;
        cin >> s >> t;
        cout << lca(s, t) << "\n";
    }
}

#define debug
#define taskname "test"
signed main(){
    faster
    if (fopen(taskname".inp", "r")){
        freopen(taskname".inp", "r", stdin);
        freopen(taskname".out", "w", stdout);
    }
    int tt = 1;
    //cin >> tt;
    while (tt--){
        Init();
    }
    if (fopen("timeout.txt", "r")){
        ofstream timeout("timeout.txt");
        timeout << signed(double(clock()) / CLOCKS_PER_SEC * 1000);
        timeout.close();
        #ifndef debug
        cerr << "Time elapsed: " << signed(double(clock()) / CLOCKS_PER_SEC * 1000) << "ms\n";
        #endif // debug
    }
}

Compilation message (stderr)

plan.cpp: In function 'int main()':
plan.cpp:150:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  150 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:151:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  151 |         freopen(taskname".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46