Submission #599094

#	Time	Username	Problem	Language	Result	Execution time	Memory
599094		radal	Railway (BOI17_railway)	C++17	100 / 100	136 ms	27284 KiB

railway

#include <bits/stdc++.h>
//#pragma GCC target("sse,sse2,avx2")
#pragma GCC optimize("unroll-loops,O3")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
constexpr int N = 1e5+20,mod = 1e9+7,inf = 1e9+10,sq = 500;
inline int mkay(int a,int b){
    if (a+b >= mod) return a+b-mod;
    if (a+b < 0) return a+b+mod;
    return a+b;
}
 
inline int poww(int a,int k){
    if (k < 0) return 0;
    int z = 1;
    while (k){
        if (k&1) z = 1ll*z*a%mod;
        a = 1ll*a*a%mod;
        k >>= 1;
    } 
    return z; 
}
int tin[N],T,par[N][20],h[N],calc[N],k;
vector<pll> adj[N];
vector<int> ans;
inline int lca(int u,int v){
    if (h[u] > h[v]) swap(u,v);
    repr(i,19,0){
        if (h[v]-h[u] >= (1 << i))
            v = par[v][i];
    }
    if (u == v) return v;
    repr(i,19,0){
        if (par[v][i] != par[u][i]){
            v = par[v][i];
            u = par[u][i];
        }
    }
    return par[v][0];
}
void dfs2(int v,int p){
    for (pll u : adj[v]){
        if (u.X != p){
            dfs2(u.X,v);
            if (calc[u.X]/2 >= k) ans.pb(u.Y);
            calc[v] += calc[u.X];
        }
    }
} 
void dfs(int v,int p){
    par[v][0] = p;
    tin[v] = T;
    T++;
    for (pll u : adj[v]){
        if (u.X != p){
            h[u.X] = h[v]+1;
            dfs(u.X,v);
        }
    }
}
inline bool cmp(int i,int j){
    return (tin[i] < tin[j]);
}
int main(){
    ios :: sync_with_stdio(0); cin.tie(0);
    int n,m;
    cin >> n >> m >> k;
    rep(i,1,n){
        int u,v;
        cin >> u >> v;
        adj[u].pb({v,i});
        adj[v].pb({u,i});
    }
    dfs(1,0);
    rep(j,1,20){
        rep(i,2,n+1)
            par[i][j] = par[par[i][j-1]][j-1];
    }
    rep(x,0,m){
        int s;
        cin >> s;
        vector<int> ve;
        rep(j,0,s){
            int v;
            cin >> v;
            ve.pb(v);
        }
        sort(all(ve),cmp);
        rep(i,1,s){
            int u = ve[i],v = ve[i-1],w = lca(u,v);
            if (w == v){
                calc[u]++;
                calc[v]--;
                continue;
            }
            calc[v]++;
            calc[u]++;
            calc[w] -= 2;
        }
        int u = ve[s-1],v = ve[0],w = lca(u,v);
        if (v == w){
            calc[u]++;
            calc[v]--;
            continue;
        }
        calc[u]++;
        calc[v]++;
        calc[w] -= 2;
    }
    dfs2(1,0);
    sort(all(ans));
    cout << ans.size() << endl;
    for (int i : ans) cout << i << ' ';
}

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