Submission #535219

#	Time	Username	Problem	Language	Result	Execution time	Memory
535219		NaimSS	007 (CEOI14_007)	C++14	30 / 100	229 ms	25616 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 d[N];
int vis[N];
    int n,m;

vi g[N];

vi dist(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;
}
set<int> S[N];

int32_t main(){
    fastio;
    cin >> n >> m;
    int s,d,a,b;
    cin >> s >> d >> a >> b;
    assert(a!=b);
    while(m--){
      int u,v;
      cin >> u >> v;
      if(v==a || v==b)S[u].insert(v);
      if(u==a || u==b)S[v].insert(u);
      g[u].pb(v);
      g[v].pb(u);
    }
    vi d1 = dist(s),d2=dist(d);

    int l = 0,r = n,ans = -1;
    dbg(d1[a],d2[a],d1[b],d2[b]);
    vi good;
    rep(i,1,n+1)if(sz(S[i]) == 2)good.pb(i);
    while(l<=r){
      int m =(l+r)/2;
      int bom=0;
      if(d1[a]+m <= d2[a] && d1[b] + m < d2[b])bom=1;
      swap(a,b);
      if(d1[a]+m <= d2[a] && d1[b] + m < d2[b])bom=1;
      swap(a,b);
      for(auto to : good){
        if(d1[to] + m < d2[a] && d1[to] + m < d2[b])bom = 1;
      }
      dbg(m,bom);
      if(bom){
        ans = m;
        l = m+1;
      }else r=m-1;
    }
    cout << ans << endl;

    // math -> gcd it all
    // Did u check N=1? Did you switch N,M?
}

Compilation message (stderr)

007.cpp: In function 'int32_t main()':
007.cpp:50:18: warning: statement has no effect [-Wunused-value]
   50 | #define dbg(...) 42
      |                  ^~
007.cpp:97:5: note: in expansion of macro 'dbg'
   97 |     dbg(d1[a],d2[a],d1[b],d2[b]);
      |     ^~~
007.cpp:50:18: warning: statement has no effect [-Wunused-value]
   50 | #define dbg(...) 42
      |                  ^~
007.cpp:110:7: note: in expansion of macro 'dbg'
  110 |       dbg(m,bom);
      |       ^~~

• Subtask 1: 9 / 30
• Subtask 2: 21 / 70