Submission #1151173

#	Time	Username	Problem	Language	Result	Execution time	Memory
1151173		vladilius	Star Trek (CEOI20_startrek)	C++20	0 / 100	9 ms	328 KiB

startrek

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define pb push_back
#define ff first
#define ss second

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    int n; ll d; cin>>n>>d;
    vector<int> g[n + 1];
    for (int i = 1; i < n; i++){
        int u, v; cin>>u>>v;
        g[u].pb(v);
        g[v].pb(u);
    }
    
    vector<int> h(n + 1), p(n + 1);
    function<void(int, int)> dfs = [&](int v, int pr){
        h[v] = 1; p[v] = pr;
        for (int i: g[v]){
            if (i == pr) continue;
            dfs(i, v);
            h[v] = min(h[v], h[i]);
        }
        h[v] = !h[v];
    };
    
    vector<int> f(n + 1);
    int c1 = 0, c0 = 0;
    for (int i = 1; i <= n; i++){
        dfs(i, 0);
        f[i] = h[i];
        if (f[i]) c1++;
        else c0++;
    }
    
    dfs(1, 0);
    
    vector<vector<bool>> dp(n + 1, vector<bool>(2));
    function<void(int)> fill = [&](int v){
        if (v == 1){
            dp[1][1] = 1; dp[1][0] = 0;
        }
        else {
            int s = 1;
            for (int i: g[p[v]]){
                if (i == p[p[v]] || i == v) continue;
                s = min(s, h[i]);
            }
            s = !s;
            dp[v][1] = dp[p[v]][s];
            dp[v][0] = dp[p[v]][1];
        }
        for (int i: g[v]){
            if (i == p[v]) continue;
            fill(i);
        }
    };
    fill(1);
    
    ll out = 0;
    for (int i = 1; i <= n; i++){
        int s = 1;
        for (int j: g[i]){
            if (i != p[j]){
                s = min(s, h[j]);
            }
        }
        s = !s;
        if (dp[i][s]){
            out += c1;
        }
        if (dp[i][1]){
            out += c0;
        }
    }
    cout<<out<<"\n";
}

• 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