Submission #2549364

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Source Code Expand

#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
using namespace std;
using Int = long long;
using ll = long long;
using Double = long double;
const Int INF = 1LL<<55;
const Int mod = (1e9)+7;
using P = pair<Int,Int>;
using T = tuple<Int,Int,Int>;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
ostream& operator<<(ostream& o,P p){return o<<"("<<p.first<<","<<p.second<<")";}
ostream& operator<<(ostream& o,T t){return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
istream& operator>>(istream& i,P &p){return i>>p.first>>p.second;}
ostream& operator<<(ostream& o,vector<auto> &a){Int i=0;for(auto t:a)o<<(i++?" ":"")<<t;return o;}
istream& operator>>(istream& i,vector<auto> &a){for(auto &t:a)i>>t;return i;}
void prArr(auto a,string s=" "){Int i=0;for(auto t:a)cout<<(i++?s:"")<<t;cout<<endl;}

Int sim(vector<Int> A){
  Int n = A.size();
  for(Int i=0;i<n;i++) assert(A[i] == 0 || A[i] == 1);
  
  cout<<A<<endl;
  while(A.size() != 1){
    n = A.size();
    vector<Int> nA;
    for(Int i=0;i<n-2;i++){
      vector<Int> a = {A[i],A[i+1],A[i+2]};
      sort(a.begin(), a.end());
      nA.push_back(a[1]);
    }
    A = nA;
    cout<<A<<endl;
  }
  cout<<A<<endl;
  return A[0];
}

signed main(){
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);
 
  Int n;
  cin>>n;
  n = 2 * n - 1;
  vector<Int> A(n);
  cin>>A;

  auto getDis = [&](const vector<Int> &X, Int num){
    Int res = INF;
    Int n = X.size();
    for(Int i=0;i<n-1;i++) {
      if(X[i] == num && X[i+1] == num) Min(res, abs(n/2 - i));
      if(X[i] == num && X[i+1] == num) Min(res, abs(n/2 - i+1));
    }
    return res;
  };
  
  auto check=[&](Int x){
    vector<Int> X(n);
    for(Int i=0;i<n;i++) X[i] = A[i] >= x;
    
    {
      Int flag = 1;
      for(Int i=0;i<n-1;i++) flag &= X[i] != X[i+1];
      if(flag) return X[0];
    }
    
    Int one = getDis(X, 1);
    Int zero = getDis(X, 0);
    assert(one != zero);
    return (Int)(one < zero);
  };
  
  Int L = 1, R = n;
  while(L+1 < R){
    Int M = (L+R)/2;
    check(M)? L = M: R = M;
  }

  Int ans = L;
  cout<<ans<<endl;
  
  return 0;
}

Submission Info

Judge Result