Submission #892075

#	Time	Username	Problem	Language	Result	Execution time	Memory
892075		kh0i	Evacuation plan (IZhO18_plan)	C++17	100 / 100	370 ms	146680 KiB

plan

#include "bits/stdc++.h"
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif

using ll = long long;
using pii = pair<int, int>;

#define F first
#define S second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
    assert(l <= r);
    return uniform_int_distribution<ll> (l, r)(rng);
}

const int N = 1e5 + 3;

int n, m, k, q;
int p[N];
ll dist[N];
vector<pair<int, ll>> g[N];

struct DSU_Rollback{
    struct Data{
        int u, sz_u, v, sz_v;
    };
 
    int n;
    vector<int> p, sz;
    vector<Data> op;
    int comps;
 
    void init(int _n){
        n = _n;
        p.clear();
        sz.clear();
        p.resize(n + 2, 0);
        sz.resize(n + 2, 1);
        comps = n;
        iota(all(p), 0);
    }
 
    // no path compression
    int find_set(int u){
        return u == p[u] ? u : find_set(p[u]);
    }
 
    bool join_sets(int u, int v){
        u = find_set(u);
        v = find_set(v);
        if(u == v)
            return 0;
        --comps;
        if(sz[u] < sz[v])
            swap(u, v);
        op.push_back({u, sz[u], v, sz[v]});
        p[v] = u;
        sz[u] += sz[v];
        return 1;
    }

    bool same_set(int u, int v){
        return find_set(u) == find_set(v);
    }
 
    void rollback(){
        if(op.empty())
            return;
        Data &x = op.back();
        p[x.u] = x.u;
        p[x.v] = x.v;
        sz[x.u] = x.sz_u;
        sz[x.v] = x.sz_v;
        ++comps;
        op.pop_back();
    }
};

namespace Sub12{
    bool valid_input(){
        return (n <= 20 and m <= 200 and q <= 200) or q == 1;
    }

    void dijkstra(){
        priority_queue<pair<ll, int>> pq;
        memset(dist, 0x3f3f3f3f, sizeof(dist));
        for(int i = 1; i <= k; ++i){
            dist[p[i]] = 0;
            pq.push({-dist[p[i]], p[i]});
        }

        while(!pq.empty()){
            int u = pq.top().S;
            pq.pop();

            for(auto [v, w] : g[u]){
                if(dist[v] > dist[u] + w){
                    dist[v] = dist[u] + w;
                    pq.push({-dist[v], v});
                }
            }
        }
    }

    void solve(){
        dijkstra();
        for(int i = 1; i <= n; ++i)
            debug(i, dist[i]);
        DSU_Rollback dsu;

        while(q--){
            int s, t;
            cin >> s >> t;

            ll l = 0, r = 1e14, res = 1e14;
            while(l <= r){
                ll mid = (l + r) / 2;
                dsu.init(n);

                for(int i = 1; i <= n; ++i)
                    if(dist[i] >= mid)
                        for(auto [v, w] : g[i])
                            if(dist[v] >= mid)
                                dsu.join_sets(i, v);

                if(dsu.same_set(s, t)){
                    res = mid;
                    l = mid + 1;
                }
                else
                    r = mid - 1;
            }
            cout << res << '\n';
        }
    }
}

struct Edge{
    int u, v;
    ll mn;
};

struct Query{
    int s, t, id;
};

vector<Query> d;
vector<Edge> e;
map<int, int> mp[N];

namespace Sub3{
    DSU_Rollback dsu;
    vector<ll> dif_dist;
    ll ans[N];

    void calc(int l, int r, vector<Edge> &e, vector<Query> &d){
        if(l + 1 == r or d.empty()){
            for(auto& [s, t, id] : d)
                ans[id] = dif_dist[l];
            return;
        }
        int mid = (l + r) / 2;
        ll mxw = dif_dist[mid];

        vector<Edge> el, er;
        vector<Query> dl, dr;

        int cnt_add = 0;

        for(auto &x : e){
            if(x.mn >= mxw){
                cnt_add += dsu.join_sets(x.u, x.v);
                er.push_back(x);
            }
            else
                el.push_back(x);
        }

        for(auto &x : d){
            if(dsu.same_set(x.s, x.t))
                dr.push_back(x);
            else
                dl.push_back(x);
        }

        calc(l, mid, el, dl);
        while(cnt_add--)
            dsu.rollback();
        calc(mid, r, er, dr);
    }

    void dijkstra(){
        priority_queue<pair<ll, int>> pq;
        memset(dist, 0x3f3f3f3f, sizeof(dist));
        for(int i = 1; i <= k; ++i){
            dist[p[i]] = 0;
            pq.push({-dist[p[i]], p[i]});
        }

        while(!pq.empty()){
            int u = pq.top().S;
            pq.pop();

            for(auto [v, w] : g[u]){
                if(dist[v] > dist[u] + w){
                    dist[v] = dist[u] + w;
                    pq.push({-dist[v], v});
                }
            }
        }
    }

    void solve(){
        dsu.init(n);
        dijkstra();
        for(int i = 1; i <= n; ++i)
            for(auto& [v, w]: g[i])
                if(i > v)
                    e.push_back({i, v, min(dist[i], dist[v])});
        for(int i = 1; i <= q; ++i){
            int s, t;
            cin >> s >> t;
            d.push_back({s, t, i});
        }
        for(int i = 1; i <= n; ++i)
            dif_dist.push_back(dist[i]);
        sort(all(dif_dist));
        dif_dist.resize(unique(all(dif_dist)) - dif_dist.begin());
        calc(0, sz(dif_dist), e, d);
        for(int i = 1; i <= q; ++i)
            cout << ans[i] << '\n';
    }
}

void read_input(){
    cin >> n >> m;
    for(int i = 1; i <= m; ++i){
        int u, v, w;
        cin >> u >> v >> w;
        if(u == v)
            continue;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    
    cin >> k;
    for(int i = 1; i <= k; ++i)
        cin >> p[i];
    cin >> q;
}

void solve(){
    read_input();
    #ifdef LOCAL
        cerr << "\n[Input Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
    #endif
    Sub3::solve();
}

int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(0);
    #define task "troll"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int test = 1;
//    cin >> test;
    for(int i = 1; i <= test; ++i){
//        cout << "Case #" << i << ": ";
        solve();
    }
    #ifdef LOCAL
        cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
    #endif
    return 0;
}

Compilation message (stderr)

plan.cpp: In function 'int32_t main()':
plan.cpp:272:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  272 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:273:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  273 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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