Submission #552559

#	Time	Username	Problem	Language	Result	Execution time	Memory
552559		Vladth11	Railway (BOI17_railway)	C++14	100 / 100	140 ms	26416 KiB

railway

#include <bits/stdc++.h>
#define debug(x) cerr << #x << " " << x << "\n"
#define debugs(x) cerr << #x << " " << x << " "
 
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <long double, pii> muchie;
 
const ll NMAX = 100001;
const ll VMAX = 1001;
const ll INF = (1LL << 60);
const ll MOD = 998244353;
const ll BLOCK = 447;
const ll base = 31;
const ll nr_of_bits = 21;
 
vector <int> sol;
vector <pii> v[NMAX];
int dp[NMAX][nr_of_bits + 1];
int sum[NMAX];
pii timp[NMAX];
int stamp;
 
bool isParent(int a, int b){
    return (timp[a].first <= timp[b].first && timp[b].second <= timp[a].second);
}
 
int LCA(int a, int b){
    int r = a, pas = nr_of_bits;
    while(pas >= 0){
        int nxt = dp[r][pas];
        if(nxt != 0 && !isParent(nxt, b))
            r = nxt;
        pas--;
    }
    if(!isParent(r, b))
        r = dp[r][0];
    return r;
}
 
void DFS(int node, int p){
    dp[node][0] = p;
    timp[node].first = ++stamp;
    for(auto x : v[node]){
        if(x.first == p) continue;
        DFS(x.first, node);
    }
    timp[node].second = stamp;
}
 
int c[NMAX];
 
bool cmp(int a, int b){
    return timp[a].first < timp[b].first;
}
 
int k;
 
void Solve(int node, int p){
    for(auto x : v[node]){
        if(x.first == p) continue;
        Solve(x.first, node);
        sum[node] += sum[x.first];
        if(sum[x.first] >= k){
            sol.push_back(x.second);
        }
    }
}
 
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, m, i;
    cin >> n >> m >> k;
    for(i = 1; i < n; i++){
        int a, b;
        cin >> a >> b;
        v[a].push_back({b, i});
        v[b].push_back({a, i});
    }
    DFS(1, 0);
    for(int j = 1; j <= nr_of_bits; j++){
        for(i = 1; i <= n; i++){
            dp[i][j] = dp[dp[i][j - 1]][j - 1];
        }
    }
    for(i = 1; i <= m; i++){
        int t;
        cin >> t;
        for(int j = 1; j <= t; j++) cin >> c[j];
        vector <int> total, stiva;
      	sort(c + 1, c + t + 1, cmp);
        total.push_back(c[t]);
        for(int j = 1; j < t; j++){
            total.push_back(c[j]);
            total.push_back(LCA(c[j], c[j + 1]));
        }
        sort(total.begin(), total.end(), cmp);
        for(int j = 0; j < total.size(); j++){
            if(j > 0 && timp[total[j - 1]].first == timp[total[j]].first)
                continue;
            while(stiva.size() && timp[stiva.back()].second < timp[total[j]].first)
                stiva.pop_back();
            if(stiva.size()){
                sum[stiva.back()]--;
                sum[total[j]]++;
            }
            stiva.push_back(total[j]);
        }
    }
    Solve(1, 0);
    sort(sol.begin(), sol.end());
    cout << sol.size() << "\n";
    for(auto x : sol) cout << x << " ";
    return 0;
}

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:101:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |         for(int j = 0; j < total.size(); j++){
      |                        ~~^~~~~~~~~~~~~~

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