Submission #218308

#	Time	Username	Problem	Language	Result	Execution time	Memory
218308		alishahali1382	007 (CEOI14_007)	C++14	100 / 100	300 ms	18040 KiB

007

#include <bits/stdc++.h>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;

const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 200010, LOG=20;

int n, m, k, u, v, x, y, t, a, b, ans;
int dist[4][MAXN];
vector<int> G[MAXN];
queue<int> Q;

void BFS(int* dist, int src){
	dist[src]=0;
	Q.push(src);
	while (Q.size()){
		int v=Q.front();
		Q.pop();
		for (int u:G[v]) if (dist[v]+1<dist[u]){
			dist[u]=dist[v]+1;
			Q.push(u);
		}
	}
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	memset(dist, 31, sizeof(dist));
	cin>>n>>m>>k>>t>>a>>b;
	while (m--){
		cin>>u>>v;
		G[u].pb(v);
		G[v].pb(u);
	}
	BFS(dist[0], a);
	BFS(dist[1], b);
	BFS(dist[2], k);
	BFS(dist[3], t);
	
	int fk=inf, ft=inf;
	if (dist[0][k]==dist[1][k]){
		for (int v=1; v<=n; v++){
			if (dist[0][v]==dist[1][v] && dist[0][v]+dist[2][v]==dist[0][k]) fk=min(fk, dist[0][v]);
		}
	}
	if (dist[0][t]==dist[1][t]){
		for (int v=1; v<=n; v++){
			if (dist[0][v]==dist[1][v] && dist[0][v]+dist[3][v]==dist[0][t]) ft=min(ft, dist[0][v]);
		}
	}
	
	int dt=min(dist[0][t], dist[1][t]), dk=min(dist[0][k], dist[1][k]);
	ans=dt-dk;
	if (fk==inf && ft==inf){
		int optk=(dist[1][k]==dk);
		int optt=(dist[1][t]==dt);
		ans-=(optk!=optt);
	}
	else ans-=(fk>ft);
	
	if (ans<0) ans=-1;
	cout<<ans<<'\n';
	
	
	return 0;
}

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