Submission #610521

#	Time	Username	Problem	Language	Result	Execution time	Memory
610521		Arnch	Mousetrap (CEOI17_mousetrap)	C++17	25 / 100	764 ms	64088 KiB

mousetrap

// oooo
/*
 har chi delet mikhad bebar ~
 gitar o ba khodet nabar! ~
 ;Amoo_Hasan;
*/

#include<bits/stdc++.h>
//#pragma GCC optimize("O3,no-stack-protector,unroll-loops")
//#pragma GCC target("avx2,fma")

using namespace std;

typedef long long ll;
typedef long double ld;

#define Sz(x) int((x).size())
#define All(x) (x).begin(), (x).end()
#define wtf(x) cout<<#x <<" : " <<x <<endl

constexpr ll inf = 1e18, N = 1e6 + 10, mod = 1e9 + 7, pr = 1000696969;

bool flag = false, mark[N];
int dp[N], par[N];
vector<int> adj[N];

void dfs(int x, int p = 0) {
	par[x] = p;

	int tim = 0;
	vector<int> vc;
	for(auto j : adj[x]) {
		if(j == p) continue;
		tim++;
		dfs(j, x);
		vc.push_back(dp[j]);
	}

	sort(All(vc), greater<int>());
	
	if(tim == 0) {
		dp[x] = 0;
		return;
	}
	if(tim == 1) {
		dp[x] = 1;
		return;
	}

	dp[x] = tim;
	dp[x] += vc[1];
}

int main() {
    ios :: sync_with_stdio(0), cin.tie(0);

	int n, t, m; cin >>n >>t >>m;
	for(int i = 0; i < n - 1; i++) {
		int u, v; cin >>u >>v;
		adj[u].push_back(v), adj[v].push_back(u);
		if(u == t && v == m) flag = true;
		if(u == m && v == t) flag = true;
	}

	dfs(t);

	int ans = dp[m];

	mark[m] = 1;
	
	int x = par[m];

	while(x != 0) {
		vector<int> vc;
		for(auto j : adj[x]) {
			if(mark[j] || j == par[x]) continue;
			vc.push_back(dp[j]);
		}
		sort(All(vc), greater<int>());
		ans += Sz(vc);
		if(Sz(vc) >= 2) ans += vc[1];

		mark[x] = 1;
		x = par[x];
	}

	cout<<ans;

    return 0;
}

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