Submission #535247

#	Time	Username	Problem	Language	Result	Execution time	Memory
535247		NaimSS	007 (CEOI14_007)	C++14	100 / 100	232 ms	16960 KiB

007

#include <bits/stdc++.h>
#define ld long double
#define endl "\n"
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pb push_back
#define mp(a,b) make_pair(a,b)
#define ms(v,x) memset(v,x,sizeof(v))
#define all(v) v.begin(),v.end()
#define ff first
#define ss second
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define per(i, a, b) for(int i = b-1; i>=a ; i--)
#define trav(a, x) for(auto& a : x)
#define allin(a , x) for(auto a : x)
#define Unique(v) sort(all(v));v.erase(unique(all(v)),v.end());
#define sz(v) ((int)v.size())
using namespace std;
typedef vector<int> vi;
#define y1 abacaba
//#define left oooooopss
#define db(x) cerr << #x <<" == "<<x << endl;
#define db2(x,y) cerr<<#x <<" == "<<x<<", "<<#y<<" == "<<y<<endl;
#define db3(x,y,z) cerr << #x<<" == "<<x<<", "<<#y<<" == "<<y<<", "<<#z<<" == "<<z<<endl;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
std::mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
ll cdiv(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll fdiv(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down
inline ll mod(ll n, ll m ){ ll ret = n%m; if(ret < 0) ret += m; return ret; }
ll gcd(ll a, ll b){return (b == 0LL ? a : gcd(b, a%b));}
ll exp(ll b,ll e,ll m){
  b%=m;
  ll ans = 1;
  for (; e; b = b * b % m, e /= 2)
      if (e & 1) ans = ans * b % m;
  return ans;
}

// debug:
void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T){ 
  cerr << ' ' << H; 
  dbg_out(T...); 
}
#ifdef LOCAL
#define dbg(...) cerr<<"(" << #__VA_ARGS__<<"):" , dbg_out(__VA_ARGS__) , cerr << endl
#else
#define dbg(...) 42
#endif
//

const int N = 200100;
    int n,m;

vi g[N];

vi dista(int a){
  vector<int> d(n+2);
  rep(i,1,n+1)d[i] = 1e9;
  d[a] = 0;
  priority_queue<pii,vector<pii>,greater<pii>> pq;
  pq.push(pii(d[a],a));
  while(!pq.empty()){
    auto t = pq.top();pq.pop();
    if(t.ff != d[t.ss])continue;
    int v = t.ss;
    for(auto to : g[v])if(d[to] > d[v] + 1){
      d[to] = d[v] + 1;
      pq.push(pii(d[to],to));
    }
  }
  return d;
}

int s,d,a,b;
vi d1,d2;
int vis[N];
int getcommon(int ini){
  rep(i,0,N)vis[i]=0;
  queue<int> q;
  q.push(ini);
  vis[ini] = 1;
  int res=0;
  while(!q.empty()){
    int v = q.front();
    q.pop();
    res=max(res,d1[ini] - d1[v]);
    for(auto to : g[v])
    if(!vis[to] && d1[to] == d1[v] - 1 && d2[to] == d2[v] - 1){
      vis[to]=1;q.push(to);
    }
  }
  return res;
}

int32_t main(){
    fastio;
    cin >> n >> m;
    cin >> s >> d >> a >> b;
    assert(a!=b);
    while(m--){
      int u,v;
      cin >> u >> v;
      g[u].pb(v);
      g[v].pb(u);
    }
    d1 = dista(a),d2=dista(b);
    int A = d1[d] - d1[s];
    int B = d2[d] - d2[s];
    if(A!=B){
      cout << max(min(A,B),-1) << endl;
    }else{
      cout << max(A - ((A + getcommon(s) < getcommon(d)) ? 1 : 0),-1) << endl;
    }
    // math -> gcd it all
    // Did u check N=1? Did you switch N,M?
}

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