Submission #894058

#	Time	Username	Problem	Language	Result	Execution time	Memory
894058		vjudge1	Railway (BOI17_railway)	C++17	100 / 100	92 ms	54100 KiB

railway

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define P ord[in[n]=++cnt]=n,tb[cnt][0]={d,n};
#define N 100100
vector<pair<int,int>> adj[N];
int cnt, ord[2*N], sum[2*N], k, ans, in[N];
set<int> edges;
pair<int,int> tb[2*N][20];
int lca(int l, int r) {
    if(l>r)swap(l,r);
    int x = 31-__builtin_clz(r-l+1);
    return min(tb[l][x],tb[r-(1<<x)+1][x]).second;
}
void dfs1(int n, int p, int d) {
    P
    for(auto [i,j]: adj[n]) 
        if(i-p)
            dfs1(i,n,d+1),P;
}
void dfs2(int n, int p, int id) {
    for(auto [i,j]: adj[n])
        if(i-p)
            dfs2(i,n,j),sum[n]+=sum[i];
    if(sum[n]>=k)
        ans++, edges.insert(id);
}
void deputy() {
    int n;
    cin >> n;
    vector<int> v;
    for(int i = 0; i < n; i++) {
        int x;
        cin >> x;
        v.pb(in[x]);
        sum[x]++;
    }
    sort(v.begin(),v.end());
    v.pb(v[0]);
    for(int i = 0; i < n; i++)
        sum[lca(v[i],v[i+1])]--;
}
int main() {
    cin.sync_with_stdio(0);
    cin.tie(0);
    int n, m;
    cin >> n >> m >> k;
    for(int i = 1; i < n; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].pb({b,i});
        adj[b].pb({a,i});
    }
    dfs1(1,0,1);
    for(int i = 1; i < 20; i++)
        for(int j = 1; j+(1<<i)<=2*n; j++)
            tb[j][i]=min(tb[j][i-1],tb[j+(1<<i-1)][i-1]);
    while(m--)
        deputy();
    dfs2(1,0,0);
    cout << ans << '\n';
    for(auto i: edges)
        cout << i << ' ';
}

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:57:47: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   57 |             tb[j][i]=min(tb[j][i-1],tb[j+(1<<i-1)][i-1]);
      |                                              ~^~

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