Submission #1199217

#	Time	Username	Problem	Language	Result	Execution time	Memory
1199217		enzy	Railway (BOI17_railway)	C++20	100 / 100	243 ms	41256 KiB

railway

#include<bits/stdc++.h>
using namespace std;
const int maxn=1e5+10;
map<pair<int,int>,int>imp;
set<pair<int,int>>s[maxn];
int minister[maxn], marc[maxn], tira[maxn], k;
vector<int>v[maxn], resp;
void merge(int pai, int filho){
    int swp=0;
    if(s[filho].size()>s[pai].size()){
        swap(filho,pai);
        swp++;
    }
    for(pair<int,int>p : s[filho]){
        auto f=s[pai].lower_bound({p.first,0});
        if(f==s[pai].end()||f->first!=p.first) s[pai].insert(p);
        else{
            if(f->second+p.second==minister[p.first]) tira[pai]++;
            s[pai].insert({p.first,p.second+f->second});
            s[pai].erase(f);
        }
    }
    if(swp){
        swap(s[pai],s[filho]);
        swap(pai,filho);
    }
    s[filho].clear();
}
void dfs(int u, int pai){
    marc[u]++;
    for(int viz : v[u]){
        if(viz==pai) continue;
        dfs(viz,u);
        merge(u,viz);
        tira[u]+=tira[viz];
    }
    //cout << u << " " << s[u].size() << " " << tira[u] << endl;
    if(s[u].size()-tira[u]>=k){
        resp.push_back(imp[{u,pai}]); 
    }
}
int main(){
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
    int n, m; cin >> n >> m >> k;
    for(int i=1;i<n;i++){
        int a, b; cin >> a >> b;
        v[a].push_back(b); v[b].push_back(a);
        imp[{a,b}]=imp[{b,a}]=i;
    }
    for(int i=1;i<=m;i++){
        int x; cin >> x;
        for(int j=1;j<=x;j++){
            int a; cin >> a;
            s[a].insert({i,1});
        }
        minister[i]=x;
    }
    dfs(1,0);
    sort(resp.begin(),resp.end());
    cout << resp.size() << endl;
    for(int a : resp) cout << a << " ";
    cout << endl;
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25