Submission #1053237

#	Time	Username	Problem	Language	Result	Execution time	Memory
1053237		steveonalex	Mousetrap (CEOI17_mousetrap)	C++17	25 / 100	447 ms	73296 KiB

mousetrap

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

const int N = 1e6 + 69;
int n, s, t;
vector<int> graph[N];
int dp[N];

bool find_t(int u, int p){
    if (u == t) return true;
    bool check = false;
    for(int v: graph[u]) if (v != p) 
        check = check || find_t(v, u);
    return check;
}

void dfs(int u, int p){
    for(int v: graph[u]) if (v != p) dfs(v, u);
    if (graph[u].size() <= 1) return;
    vector<int> toxic;
    for(int v: graph[u]) if (v != p) toxic.push_back(dp[v]);
    sort(ALL(toxic), greater<int>());
    dp[u] = toxic[1] + toxic.size();
}

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 
    clock_t start = clock();

    cin >> n >> s >> t;
    if (s == t){
        cout << 0 << "\n";
        return 0;
    }
    for(int i = 1; i<n; ++i){
        int u, v; cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    int branch = -1;
    for(int v: graph[s]){
        if (find_t(v, s)) branch = v;
    }
    graph[s] = {branch};

    if (branch != t) exit(1);

    dfs(t, s);

    cout << dp[t] << "\n";


    cerr << "Time elapsed: " << clock() - start << " ms!\n";
    return 0;
}

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