Submission #813789

#	Time	Username	Problem	Language	Result	Execution time	Memory
813789		vjudge1	Monochrome Points (JOI20_monochrome)	C++17	25 / 100	2043 ms	340 KiB

monochrome

#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
  #include "/home/trucmai/.vim/tools.h"
  #define debug(x...) cerr << "\e[91m"<<__func__<<":"<<__LINE__<<" [" << #x << "] = ["; _print(x); cerr << "\e[39m" << endl;
  #else
  #define debug(x...)
#endif

void open(){
  if(fopen("i.inp","r")){
    freopen("i.inp","r",stdin);
    freopen("o.out","w",stdout);
  }
}

#define ll long long
#define all(a) (a).begin(), (a).end()
#define vi vector<ll>
#define pi pair<ll,ll>
#define pii pair<ll,pair<ll,ll>>
#define fi first
#define se second
#define gcd __gcd
#define mset(a,v) memset(a, v, sizeof(a))
#define endl '\n'
#define spc " "

const int MN = 1e6 + 5,LOG = 27;
const ll MOD = 1e9 + 7,INF = 1e9;
ll n; string s;
vector<ll>b,w;
bool cross(ll x1,ll y1,ll x2,ll y2){
    if(x1 > y1) swap(x1, y1);
    if(x2 > y2) swap(x2, y2);
    if(x1 < x2 && y2 < y1) return false;
    if(x2 < x1 && y1 < y2) return false;
    if(x1 > y2 || x2 > y1) return false;
    return true;
} 
void solve(){
  cin>>n>>s; 
  for(ll i = 0;i < 2*n;++i){ 
    if(s[i] == 'B') b.push_back(i); 
    else w.push_back(i);
  }
  sort(all(b)); sort(all(w));
  //sub 2: best strats: w[i] -> b[i+k]
  ll res = 0;
  for(ll k = 0;k < n;++k){ 
    ll cnt = 0; 
    for(ll i = 0;i < n;++i)
      for(ll j = i+1;j < n;++j)
        if(cross(w[i],b[(i+k)%n],w[j],b[(j+k)%n])) ++cnt;
    res = max(res,cnt);
  }
  cout<<res<<endl;
}

signed main(){
  cin.tie(0) -> sync_with_stdio(0);
  open();
  ll t = 1; //cin>>t;
  while(t--) solve(); 
  
  #ifdef LOCAL
    cerr << endl << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
  #endif
}

Compilation message (stderr)

monochrome.cpp: In function 'void open()':
monochrome.cpp:13:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     freopen("i.inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~
monochrome.cpp:14:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |     freopen("o.out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 21 / 21
• Subtask 3: 0 / 10
• Subtask 4: 0 / 65