Submission #110789

#	Time	Username	Problem	Language	Result	Execution time	Memory
110789		MAMBA	007 (CEOI14_007)	C++17	100 / 100	346 ms	42360 KiB

007

#include <bits/stdc++.h> 

using namespace std;

#define rep(i , j , k) for (int i = j; i < (int)k; i++)
#define pb push_back
#define mt make_tuple
#define for_all(x) x.begin(),x.end()

typedef long long ll;
typedef pair<int , int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef long double ld;
typedef complex<ld> point;

inline void fileIO(string s) {
	freopen((s + ".in").c_str(), "r", stdin);
	freopen((s + ".out").c_str(), "w", stdout);
}

template<class T , class S>
inline bool smin(T &a, S b) { return (T)b < a ? a = b , 1 : 0; }
template<class T , class S>
inline bool smax(T &a, S b) { return a < (T)b ? a = b , 1 : 0; }

constexpr int N = 1e6 + 10;

constexpr int MOD = 1e9 + 7;

template<typename T>
inline T mod(T &v) { return v = (v % MOD + MOD) % MOD; }
template<typename S, typename T>
inline S add(S &l, T r) { return mod(l += r); }

ll po(ll v, ll u) { return u ? po(v * v % MOD , u >> 1) * (u & 1 ? v : 1) % MOD : 1; }

int n , m;
int s , t , a , b, dist[N];
vector<int> adj[N];
int L , R , Q[N];

void bfs(int so) {
	memset(dist , -1, sizeof(dist));
	dist[so] = 0;
	L = 0, R = 1;
	Q[0] = so;
	while (L < R) {
		int me = Q[L++];
		for (auto e : adj[me])
			if (!~dist[e]) {
				dist[e] = dist[me] + 1;
				Q[R++] = e;
			}
	}
}

int arr[N];

void dfs(int v,  int col) {
	arr[v] += col;
	for (auto e : adj[v])
		if (dist[e] + 1 == dist[v] && arr[e] < col) 
			dfs(e , col);
}

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

#ifndef LOCAL
	//	fileIO("forbidden1");
#endif


	cin >> n >> m >> s >> t >> a >> b;
	rep(i , 0 , m) {
		int u , v;
		cin >> u >> v;
		adj[u].pb(v);
		adj[v].pb(u);
	}

	bfs(s);
	int A = dist[a];
	int B = dist[b];

	dfs(a , 1);
	dfs(b , 2);

	int alpha = 0;
	rep(i , 0 , n + 1)
		if (arr[i] == 3)
			smax(alpha , dist[i]);

	bfs(t);
	int C = dist[a];
	int D = dist[b];

	memset(arr , 0 , sizeof(arr));
	dfs(a , 1);
	dfs(b , 2);

	int beta = 0;
	rep(i , 0 , n + 1)
		if (arr[i] == 3)
			smax(beta , dist[i]);



	int res = min(C - A , D - B);
	if (res < 0) return cout << -1 << endl, 0;

	if (A == B && C == D && (C - beta) < (A - alpha))  
		res--;
	if (res < 0) res = -1;
	cout << res << endl;


	return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70