Submission #444917

#	Time	Username	Problem	Language	Result	Execution time	Memory
444917		JovanB	Bridges (APIO19_bridges)	C++17	59 / 100	3090 ms	406324 KiB

bridges

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

using ll = long long;
using ld = long double;

const int N = 50000;
const int M = 100000;
const int K = 500;

int ea[M+5];
int eb[M+5];
int ec[M+5];
bool changed[M+5];

int qt[M+5];
int qa[M+5];
int qb[M+5];

struct DSU{
    int n;
    int par[N+5];
    int rnk[N+5];
    int sz[N+5];
    void init(int _n){
        n = _n;
        for(int i=1; i<=n; i++){
            par[i] = i;
            rnk[i] = 0;
            sz[i] = 1;
        }
    }
    struct op{
        int a, b, rnka, rnkb, sza, szb;
    };
    stack <op> st;
    int root(int x){ return (x == par[x] ? x : root(par[x])); }
    void povezi(int a, int b){
        a = root(a);
        b = root(b);
        st.push({a, b, rnk[a], rnk[b], sz[a], sz[b]});
        if(a == b) return;
        if(rnk[a] < rnk[b]) swap(a, b);
        if(rnk[a] == rnk[b]) rnk[a]++;
        sz[a] += sz[b];
        par[b] = a;
    }
    void rollback(){
        op o = st.top();
        st.pop();
        int a = o.a;
        int b = o.b;
        rnk[a] = o.rnka;
        rnk[b] = o.rnkb;
        sz[a] = o.sza;
        sz[b] = o.szb;
        par[a] = a;
        par[b] = b;
    }

} dsu;

int sol[M+5];

const int INF = 1000000007;

vector <int> ima[M+5];
int gde[M+5];

int main(){
    ios_base::sync_with_stdio(false), cin.tie(0);
    cout.precision(10);
    cout << fixed;

    int n, m;
    cin >> n >> m;
    for(int i=1; i<=m; i++){
        cin >> ea[i] >> eb[i] >> ec[i];
    }
    int qrs;
    cin >> qrs;
    int qq = 0;
    for(int ql=1; ql<=qrs; ql+=K){
        int qr = min(qrs, ql+K-1);
        dsu.init(n);
        vector <pair <int, pair <int, int>>> vec;
        vector <int> ch;
        for(int i=ql; i<=qr; i++){
            cin >> qt[i] >> qa[i] >> qb[i];
            if(qt[i] == 1){
                if(!changed[qa[i]]) ch.push_back(qa[i]);
                changed[qa[i]] = 1;
            }
            else{
                qq++;
                gde[i] = qq;
                vec.push_back({qb[i], {qq, qa[i]}});
            }
        }
        for(int i=1; i<=m; i++){
            if(changed[i]) continue;
            vec.push_back({ec[i], {INF, i}});
        }
        sort(vec.begin(), vec.end());
        reverse(vec.begin(), vec.end());
        for(int i=ql; i<=qr; i++){
            if(qt[i] == 1) ec[qa[i]] = qb[i];
            else{
                for(auto c : ch){
                    if(ec[c] >= qb[i]) ima[gde[i]].push_back(c);
                }
            }
        }
        for(auto x : vec){
            if(x.second.first == INF) dsu.povezi(ea[x.second.second], eb[x.second.second]);
            else{
                int ind = x.second.first;
                int p = x.second.second;
                for(auto c : ima[ind]) dsu.povezi(ea[c], eb[c]);
                sol[ind] = dsu.sz[dsu.root(p)];
                for(auto c : ima[ind]) dsu.rollback();
            }
        }
        for(auto c : ch) changed[c] = 0;
        for(int i=ql; i<=qr; i++) if(gde[i]) ima[gde[i]].clear();
    }
    for(int i=1; i<=qq; i++) cout << sol[i] << "\n";
    return 0;
}

Compilation message (stderr)

bridges.cpp: In function 'int main()':
bridges.cpp:121:26: warning: unused variable 'c' [-Wunused-variable]
  121 |                 for(auto c : ima[ind]) dsu.rollback();
      |                          ^

• Subtask 1: 13 / 13
• Subtask 2: 16 / 16
• Subtask 3: 17 / 17
• Subtask 4: 0 / 14
• Subtask 5: 13 / 13
• Subtask 6: 0 / 27