Submission #623709

#	Time	Username	Problem	Language	Result	Execution time	Memory
623709		Vladth11	Star Trek (CEOI20_startrek)	C++14	0 / 100	2 ms	2644 KiB

startrek

#include <bits/stdc++.h>
#define C 1
#define P 0
#define debug(x) cerr << #x << " " << x << "\n"
#define debugs(x) cerr << #x << " " << x << " "

using namespace std;
typedef long long ll;
typedef pair <ll, ll> pii;
typedef pair <long double, pii> muchie;

const ll NMAX = 100001;
const ll VMAX = 101;
const ll INF = (1LL << 60);
const ll MOD = 1000000007;
const ll BLOCK = 447;
const ll base = 117;
const ll nr_of_bits = 18;
const ll inv2 = 500000004;

vector <int> v[NMAX];
int col[NMAX];
int children[NMAX][2];
int maximal[NMAX];
int rosii[NMAX];
int adv[NMAX];

void DFS(int node, int p){
    col[node] = P;
    for(auto x : v[node]){
        if(x == p) continue;
        DFS(x, node);
        children[node][col[x]]++;
    }
    if(children[node][C] == (int)v[node].size() - (p != 0)){
        col[node] = P;
    }else{
        col[node] = C;
    }
    if(col[node] == P)
        rosii[node] = 1;
    for(auto x : v[node]){
        if(x == p) continue;
        if(col[node] != col[x]){
            rosii[node] += rosii[x];
        }
    }
}

int perdanti = 0;

void Rerooting(int node, int p){
    adv[node] = col[node];
    if(adv[node] == P)
        perdanti++;
    for(auto x : v[node]){
        if(x == p) continue;
        int cx = col[x], cnode = col[node];
        children[node][col[x]]--;
        if(children[node][C] == v[node].size() - 1){
            col[node] = P;
        }else{
            col[node] = C;
        }
        children[x][col[node]]++;
        if(children[x][C] == v[x].size()){
            col[x] = P;
        }else{
            col[x] = C;
        }
        Rerooting(x, node);
        children[x][col[node]]--;
        col[x] = cx;
        col[node] = cnode;
        children[node][col[x]]++;
    }
}

int main() {
    //ifstream cin(".in");
    //ofstream cout(".out");
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, d, i;
    cin >> n >> d;
    for(i = 1; i < n; i++){
        int a, b;
        cin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    DFS(1, 0);
    Rerooting(1, 0);
    ll schimba = 1LL * perdanti * rosii[1];
    schimba %= MOD;
    if(col[1] == P){
        cout << schimba;
    }else{
        cout << (1LL * n * n - schimba + MOD) % MOD;
    }
    return 0;
}

Compilation message (stderr)

startrek.cpp: In function 'void Rerooting(int, int)':
startrek.cpp:60:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |         if(children[node][C] == v[node].size() - 1){
      |            ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
startrek.cpp:66:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |         if(children[x][C] == v[x].size()){
      |            ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 0 / 7
• Subtask 3: 0 / 8
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20
• Subtask 8: 0 / 15