Submission #973205

#	Time	Username	Problem	Language	Result	Execution time	Memory
973205		efedmrlr	Mousetrap (CEOI17_mousetrap)	C++17	25 / 100	727 ms	73468 KiB

mousetrap

// #pragma GCC optimize("O3,Ofast,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>

using namespace std;


#define lli long long int
#define MP make_pair
#define pb push_back
#define REP(i,n) for(int i = 0; (i) < (n); (i)++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()


void fastio() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
}


const double EPS = 0.00001;
const int INF = 1e9+500;
const int N = 1e6 + 5;
const int ALPH = 26;
const int LGN = 25;
constexpr int MOD = 1e9+7;
int n,t,m;

vector<int> dp(N, 0);
vector<vector<int> > adj(N, vector<int>());

void dfs(int node, int par) {
    for(auto c : adj[node]) {
        if(c == par) continue;
        dfs(c, node);
    }
    array<int, 2> mx = {0, 0};
    for(auto c : adj[node]) {
        if(c == par) continue;
        if(dp[c] > mx[0]) {
            swap(mx[0], mx[1]);
            mx[0] = dp[c];
        }
        else if(dp[c] > mx[1]) {
            mx[1] = dp[c];
        }
    }
    dp[node] = mx[1] + adj[node].size() - 1; 

}

inline void solve() {
    cin>>n>>t>>m;
    REP(i, n - 1) {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    dfs(m, t);
    cout << dp[m] << "\n";
}
 
signed main() {

    fastio();
    int test = 1;
    //cin>>test;
    while(test--) {
        solve();
    }
    
}

• Subtask 1: 0 / 20
• Subtask 2: 25 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35