Submission #575570

#	Time	Username	Problem	Language	Result	Execution time	Memory
575570		talant117408	Village (BOI20_village)	C++17	0 / 100	1 ms	324 KiB

Village

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
 
#define pb                  push_back
#define mp                  make_pair
#define all(v)              (v).begin(),(v).end()
#define rall(v)             (v).rbegin(),(v).rend()
#define lb                  lower_bound
#define ub                  upper_bound
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'

void solve() {
    int n;
    cin >> n;
    vector <int> graph[n];
    for (int i = 0; i < n-1; i++) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    
    int cost[2];
    cost[0] = cost[1] = 0;
    vector <vector <int>> rear(2, vector <int> (n));
    
    //~ int df = 0, vf = 0;
    //~ function <void(int, int, int)> find_furthest = [&](int v, int p, int dist) {
        //~ if (dist > df) {
            //~ df = dist;
            //~ vf = v;
        //~ }
        //~ for (auto to : graph[v]) {
            //~ if (to == p) continue;
            //~ find_furthest(to, v, dist+1);
        //~ }
    //~ };
    //~ int d1, d2;
    //~ find_furthest(0, 0, 0);
    //~ d1 = vf;
    //~ df = vf = 0;
    //~ find_furthest(d1, d1, 0);
    //~ d2 = vf;
    //~ cost[1] = df;
    //~ rear[1][d1] = d2;
    //~ rear[1][d2] = d1;
    //~ vector <int> left;
    //~ for (int i = 0; i < n; i++) {
        //~ if (i == d1 || i == d2) {
            //~ continue;
        //~ }
        //~ left.pb(i);
    //~ }
    //~ for (int i = 0; i < n-2; i++) {
        //~ rear[0][left[i]] = left[(i+1)%(n-2)];
    //~ }
    
    function <int(int, int)> find_smallest = [&](int v, int p) {
        bool available = 1;
        int child = -1;
        for (auto to : graph[v]) {
            if (to == p) continue;
            if (find_smallest(to, v)) {
                if (child == -1) {
                    child = to;
                }
                else {
                    rear[0][child] = to;
                    rear[0][to] = child;
                    child = -1;
                    cost[0] += 2;
                }
            }
        }
        if (child != -1) {
            available = 0;
            rear[0][child] = v;
            rear[0][v] = child;
            child = -1;
            cost[0] += 2;
        }
        if (!v && available) {
            available = 0;
            cost[0] += 2;
            int a, b;
            for (auto to : graph[v]) {
                if (to == p) continue;
                a = to; b = rear[0][to];
                break;
            }
            rear[0][v] = b;
            rear[0][b] = a;
            rear[0][a] = v;
        }
        return available;
    };
    
    find_smallest(0, 0);
    
    cout << cost[0] << ' ' << cost[1] << endl;
    for (int i = 0; i < 2; i++) {
        for (auto to : rear[i]) cout << to+1 << ' ';
        cout << endl;
    }
}

int main() {
    do_not_disturb
    
    int t = 1;
    //~ cin >> t;
    while (t--) {
        solve();
    }
    
    return 0;
}

Compilation message (stderr)

Village.cpp: In static member function 'static _Res std::_Function_handler<_Res(_ArgTypes ...), _Functor>::_M_invoke(const std::_Any_data&, _ArgTypes&& ...) [with _Res = int; _Functor = solve()::<lambda(int, int)>; _ArgTypes = {int, int}]':
Village.cpp:101:22: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
  101 |             rear[0][a] = v;
      |                      ^
Village.cpp:93:17: note: 'a' was declared here
   93 |             int a, b;
      |                 ^
Village.cpp:99:24: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   99 |             rear[0][v] = b;
Village.cpp:93:20: note: 'b' was declared here
   93 |             int a, b;
      |                    ^

• Subtask 1: 0 / 12
• Subtask 2: 0 / 38
• Subtask 3: 0 / 50