Submission #94525

#	Time	Username	Problem	Language	Result	Execution time	Memory
94525		jasony123123	Mousetrap (CEOI17_mousetrap)	C++11	25 / 100	1194 ms	69624 KiB

mousetrap

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
#include <array>
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
//using namespace __gnu_pbds;

#define FOR(i,start,end) for(int i=start;i<(int)(end);i++)
#define FORE(i,start,end) for(int i=start;i<=(int)end;i++)
#define RFOR(i,start,end) for(int i = start; i>end; i--)
#define RFORE(i,start,end) for(int i = start; i>=end; i--)
#define all(a) a.begin(), a.end()
#define mt make_tuple
#define mp make_pair
#define v vector
#define sf scanf
#define pf printf
#define dvar(x) cout << #x << " := " << x << "\n"
#define darr(x,n) FOR(i,0,n) cout << #x << "[" << i << "]" << " := " << x[i] << "\n"

typedef long long ll;
typedef long double ld;
typedef pair<int, int > pii;
typedef pair<ll, ll> pll;
//template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T> void minn(T &a, T b) { a = min(a, b); }
template<class T> void maxx(T &a, T b) { a = max(a, b); }

void io() {
#ifdef LOCAL_PROJECT 
	freopen("input.in", "r", stdin); freopen("output.out", "w", stdout);
#else 
	/* online submission */

#endif 
	ios_base::sync_with_stdio(false); cin.tie(NULL);
}

const ll MOD = 1000000007LL;
const ll PRIME = 105943LL;
const ll INF = 1e12;
/****************************************************************/
const int MAXN = 1e6 + 1;
int N, T, M;
v<int> adj[MAXN];

bool findpath(int p, int st, int en, v<int> &pa) {
	if (st == en) return true;
	for (auto c : adj[st]) if (c != p) {
		pa.push_back(c);
		if (findpath(st, c, en, pa))
			return true;
		else
			pa.pop_back();
	}
}

pii bad;
int moves(int x, int p) {
	v<int> cdp = { 0,0 };
	int deg = 0;
	for (auto c : adj[x]) if (c != p &&mp(c, x) != bad && mp(x, c) != bad) {
		cdp.push_back(moves(c, x));
		deg++;
	}
	sort(all(cdp), greater<int>());
	return deg + cdp[1];
}

int main() {
	io();
	cin >> N >> T >> M;
	FOR(i, 0, N - 1) {
		int a, b; cin >> a >> b;
		adj[a].push_back(b), adj[b].push_back(a);
	}
	v<int> path = { M };
	findpath(-1, M, T, path);
//	darr(path, path.size());

	int ans = 0;
	FOR(i, 0, path.size() - 1) {
		bad = { (i-1<0?-1:path[i - 1]), path[i] };
		ans += moves(path[i], path[i + 1]);
	}
	cout << ans << "\n";
}

Compilation message (stderr)

mousetrap.cpp: In function 'bool findpath(int, int, int, std::vector<int>&)':
mousetrap.cpp:57:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

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