Submission #917707

#	Time	Username	Problem	Language	Result	Execution time	Memory
917707		trMatherz	Railway (BOI17_railway)	C++17	100 / 100	212 ms	37348 KiB

railway

#include <iostream> //cin, cout

/*
#include <fstream>
std::ifstream cin ("ex.in");
std::ofstream cout ("ex.out");
*/




// includes
#include <cmath> 
#include <set>
#include <map>
#include <queue>
#include <string>
#include <vector>
#include <array>
#include <algorithm>
#include <numeric>
#include <iomanip>
#include <unordered_set>
#include <stack>
#include <ext/pb_ds/assoc_container.hpp>
#include <random>
#include <chrono>



//usings 
using namespace std;
using namespace __gnu_pbds;


// misc
#define ll long long
#define pb push_back
#define pq priority_queue
#define ub upper_bound
#define lb lower_bound
template<typename T, typename U> bool emin(T &a, const U &b){ return b < a ? a = b, true : false; }
template<typename T, typename U> bool emax(T &a, const U &b){ return b > a ? a = b, true : false; }
typedef uint64_t hash_t;

// vectors
#define vi vector<int>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define vpii vector<pair<int, int>>
#define vvpii vector<vector<pair<int, int>>>
#define vppipi vector<pair<int, pair<int, int>>>
#define vl vector<ll>
#define vvl vector<vl>
#define vvvl vector<vvl>
#define vpll vector<pair<ll, ll>>
#define vb vector<bool>
#define vvb vector<vb>
#define vs vector<string>
#define sz(x) (int)x.size()
#define rz resize
#define all(x) x.begin(), x.end()


// pairs
#define pii pair<int, int>
#define pll pair<ll, ll>
#define mp make_pair
#define f first
#define s second

// sets
#define si set<int>
#define sl set<ll>
#define ss set<string>
#define in insert
template <class T> using iset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

// maps
#define mii map<int, int>
#define mll map<ll, ll>

// loops
#define FR(x, z, y) for (int x = z; x < y; x++)
#define FRE(x, z, y) FR(x, z, y + 1)
#define F(x, y) FR(x, 0, y)
#define FE(x, y) F(x, y + 1)
#define A(x, y) for(auto &x : y)

int n, m, k;
map<pii, int> w;
vvi a, dp;
vi v, d;
vi ans, t;

int timer = 0;
void dfs(int x){
    t[x] = timer++;
    FR(i, 1, 18) dp[x][i] = dp[dp[x][i - 1]][i - 1];
    A(u, a[x]) if(u != dp[x][0]) d[u] = d[dp[u][0] = x] + 1, dfs(u);
}

int jump(int x, int v){
    F(i, 18) if((1 << i) & v) x = dp[x][i];
    return x;
}

int lca(int x, int y){
    if(d[y] > d[x]) swap(x, y);
    x = jump(x, d[x] - d[y]);
    if(x == y) return x;
    for(int i = 17; i >= 0; i--) if(dp[x][i] != dp[y][i]) x = dp[x][i], y = dp[y][i];
    return dp[x][0];
}

int go(int x){
    int cur = 0;
    A(u, a[x]) if(u != dp[x][0]) cur += go(u);
    cur += v[x];
    if(cur >= k * 2 && dp[x][0] != x) ans.pb(w[{min(dp[x][0], x), max(dp[x][0], x)}]);
    return cur;
}

int main(){
    cin >> n >> m >> k;
    a = vvi(n);
    dp = vvi(n, vi(18, 0));
    v = d = vi(n, 0);
    t = vi(n, 0);
    F(i, n - 1){
        int x, y; cin >> x >> y; x--; y--;
        if(y < x) swap(x, y);
        w[{x, y}] = i; a[x].pb(y); a[y].pb(x);
    }
    dfs(0);
    while(m--){
        int x; cin >> x;
        vi temp(x); A(u, temp) cin >> u, u--;
        sort(all(temp), [&](auto r, auto e){return t[r] < t[e];});
        int p = temp.back();
        A(u, temp){
            if(p != -1) v[u]++, v[p]++, v[lca(u, p)] -= 2;
            
            p = u;
        }
    }
    go(0);
    sort(all(ans));
    cout << sz(ans) << endl;
    A(u, ans) cout << u + 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