Submission #916305

#	Time	Username	Problem	Language	Result	Execution time	Memory
916305		GrindMachine	Bridges (APIO19_bridges)	C++17	100 / 100	2940 ms	15312 KiB

bridges

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

refs:
https://github.com/dolphingarlic/CompetitiveProgramming/blob/master/APIO/APIO%2019-bridges.cpp

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
const int B = 405;

struct DSU {
    vector<int> par, rankk, siz;
    vector<array<int,4>> history;

    DSU() {

    }

    DSU(int n) {
        init(n);
    }

    void init(int n) {
        par = vector<int>(n + 1);
        rankk = vector<int>(n + 1);
        siz = vector<int>(n + 1);
        rep(i, n + 1) create(i);
    }

    void reset(int n){
        rep(i,n+1) create(i);
        history.clear();
    }

    void create(int u) {
        par[u] = u;
        rankk[u] = 0;
        siz[u] = 1;
    }

    int find(int u) {
        if (u == par[u]) return u;
        else return find(par[u]);
    }

    bool same(int u, int v) {
        return find(u) == find(v);
    }

    void merge(int u, int v) {
        u = find(u), v = find(v);
        if (u == v) return;

        history.pb({u,par[u],rankk[u],siz[u]});
        history.pb({v,par[v],rankk[v],siz[v]});

        if (rankk[u] == rankk[v]) rankk[u]++;
        if (rankk[u] < rankk[v]) swap(u, v);

        par[v] = u;
        siz[u] += siz[v];
    }

    void rollback(){
        while(!history.empty()){
            auto [u,paru,rankku,sizu] = history.back();
            history.pop_back();
            par[u] = paru;
            rankk[u] = rankku;
            siz[u] = sizu;
        }
    }
};

void solve(int test_case)
{
    int n,m; cin >> n >> m;
    vector<array<int,3>> edges(m+5);
    rep1(i,m){
        int u,v,w; cin >> u >> v >> w;
        edges[i] = {u,v,w};
    }

    int q; cin >> q;
    vector<array<int,3>> queries(q);
    rep(i,q) rep(j,3) cin >> queries[i][j];

    set<array<int,3>> st;
    rep1(i,m){
        array<int,3> ar = {edges[i][2],2,i};
        st.insert(ar);
    }

    vector<int> ans(q,-1);
    DSU dsu(n);
    vector<bool> came(m+5);

    rep(block,ceil2(q,B)){
        dsu.reset(n);

        vector<array<int,3>> rem_edges;
        vector<array<int,3>> changed_edges;

        for(int i = block*B; i < min((block+1)*B,q); ++i){
            if(queries[i][0] == 1){
                int id = queries[i][1];
                changed_edges.pb({i,id,queries[i][2]});
                array<int,3> ar = {edges[id][2],2,id};
                if(st.count(ar)){
                    rem_edges.pb(ar);
                    st.erase(ar);
                }
            }
            else{
                auto [t,u,w] = queries[i];
                array<int,3> ar = {w,1,i};
                st.insert(ar);
            }
        }

        reverse(all(changed_edges));

        trav(ar,rem_edges){
            changed_edges.pb({block*B-1,ar[2],edges[ar[2]][2]});
        }

        for(auto it = st.rbegin(); it != st.rend(); ++it){
            auto [w,t,id] = *it;
            if(t == 2){
                auto [u,v,ww] = edges[id];
                dsu.merge(u,v);
            }
            else{
                dsu.history.clear();

                for(auto [query_id,edge_id,edge_w] : changed_edges){
                    if(query_id > id) conts;
                    if(came[edge_id]) conts;
                    came[edge_id] = 1;
                    if(edge_w >= w){
                        auto [u,v,ww] = edges[edge_id];
                        dsu.merge(u,v);
                    }
                }

                for(auto [query_id,edge_id,w] : changed_edges){
                    came[edge_id] = 0;
                }

                int u = queries[id][1];
                ans[id] = dsu.siz[dsu.find(u)];

                dsu.rollback();
            }
        }

        trav(ar,rem_edges){
            st.insert(ar);
        }

        for(int i = block*B; i < min((block+1)*B,q); ++i){
            if(queries[i][0] == 1){
                int id = queries[i][1];
                array<int,3> ar = {edges[id][2],2,id};
                st.erase(ar);
                edges[id][2] = queries[i][2];
                ar[0] = queries[i][2];
                st.insert(ar);
            }
            else{
                auto [t,u,w] = queries[i];
                array<int,3> ar = {w,1,i};
                st.erase(ar);
            }
        }
    }

    rep(i,q){
        if(ans[i] != -1){
            cout << ans[i] << endl;
        }
    }
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 16 / 16
• Subtask 3: 17 / 17
• Subtask 4: 14 / 14
• Subtask 5: 13 / 13
• Subtask 6: 27 / 27