Submission #946503

#	Time	Username	Problem	Language	Result	Execution time	Memory
946503		xynex	Monochrome Points (JOI20_monochrome)	C++17	35 / 100	2056 ms	9928 KiB

monochrome

/**
  * Author: Tenjin
  * Created: 27.04.2022 18:58
  * Why am I so stupid? :c
  * Slishkom slab
**/

#include <bits/stdc++.h>

// #pragma GCC optimize("inline")
// #pragma GCC optimize("-fgcse,-fgcse-lm")
// #pragma GCC optimize("-ftree-pre,-ftree-vrp")
// #pragma GCC optimize("-ffast-math")
// #pragma GCC optimize("-fipa-sra")
// #pragma GCC optimize("-fpeephole2")
// #pragma GCC optimize("-fsched-spec")
// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
// #pragma GCC optimize("unroll-loops")

using namespace std;

#define ll long long
#define dl double long
#define ull unsigned long long
#define pr pair
#define vt vector
#define ff first
#define ss second
#define mp make_pair
#define sz(a) (int)a.size()
#define pb push_back
#define pf push_front
#define popB pop_back
#define popF pop_front
#define bit_count __builtin_popcount
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sp(x) fixed << setprecision(x)

template<typename T> T get_rand(T l, T r) {
  random_device rd;
  mt19937 gen(rd());
  return uniform_int_distribution<T>(l, r)(gen);
}
template<typename T> T lcm(T a, T b) { return a * (b / __gcd(a, b)); }

template<class A>  void read(vt<A>& v);
template<class A, size_t S> void read(array<A, S>& a);
template<class T> void read(T& x) { cin >> x; }
void read(double& d) { string t; read(t); d = stod(t); }
void read(long double& d) { string t; read(t); d = stold(t); }
template<class H, class... T> void read(H& h, T&... t) { read(h); read(t...); }
template<class A> void read(vt<A>& x) { for (auto& a : x) read(a); }
template<class A, size_t S> void read(array<A, S>& x) { for (auto& a : x) read(a); }

string to_string(char c) { return string(1, c); }
string to_string(bool b) { return b ? "true" : "false"; }
string to_string(const char* s) { return string(s); }
string to_string(string s) { return s; }
string to_string(vt<bool> v) { string res; for (int i = 0; i < sz(v); ++i) res += char('0' + v[i]); return res; }
template<size_t S> string to_string(bitset<S> b) { string res; for (int i = 0; i < S; ++i) res += char('0' + b[i]); return res; }
template<class T> string to_string(T v) { bool f = 1; string res; for (auto x : v) { if (!f) res += ' '; f = 0; res += to_string(x); } return res; }

template<class A> void write(A x) { cout << to_string(x); }
template<class H, class... T> void write(const H& h, const T&... t) { write(h); write(t...); }

void print() { write("\n"); }
template<class H, class... T> void print(const H& h, const T&... t) { write(h); if (sizeof...(t)) write(' '); print(t...); }

void freop(string s) {
  freopen((s + ".in").c_str(), "r", stdin);
  freopen((s + ".out").c_str(), "w", stdout);
}

const int MOD = 1e9 + 7;
const ll INF = 1e14;
const dl pi = acos(-1);
const dl eps = 1e-12;
const int sq = 700;

int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};
/* ll vs int*/

const int N = 1e6 + 5;
const int M = 2e6 + 6;

int n;
vt<int> w, b;
int t[4 * N];
void upd(int pos, int val, int tl = 1, int tr = 2 * n, int v = 1) {
  if(tl == tr) t[v] = val;
  else {
    int mid = (tl + tr) >> 1;
    if(mid >= pos) upd(pos, val, tl, mid, v * 2);
    else upd(pos, val, mid + 1, tr, v * 2 + 1);
    t[v] = t[v * 2] + t[v * 2 + 1];
  }
}
int get(int l, int r, int tl = 1, int tr = 2 * n, int v = 1) {
  if(tl > r || tr < l) return 0;
  if(tl >= l && tr <= r) return t[v];
  int mid = (tl + tr) >> 1;
  return get(l, r, tl, mid, v * 2) + get(l, r, mid + 1, tr, v * 2 + 1);
}
ll get(int i) {
  vt<pr<int, int>> ord;
  for(int j = 0; j < n; ++j) {
    int X = w[j];
    int Y = b[(j + i) % n];
    if(X > Y) swap(X, Y);
    ord.pb({X, Y});
  }
  sort(all(ord));
  for(int j = 1; j <= 2 * n; ++j) upd(j, 0);
  ll ans = 0;
  for(int j = 0; j < n; ++j) {
    ans += get(ord[j].ff, ord[j].ss);
    // print(ans);
    upd(ord[j].ss, 1);
  }
  return ans;
}
void solve() {
  read(n);
  for(int i = 1; i <= 2 * n; ++i) {
    char s; read(s);
    if(s == 'B') b.pb(i);
    else w.pb(i);
  }
  ll res = 0;
   {
    int l = 0, r = n - 1;
    while((r - l) >= 0) {
      int mid = (r + l) >> 1;
      ll cur = get(mid);
      ll x = (mid == 0 ? 0 : get(mid - 1));
      ll y = (mid == (n - 1) ? 0 : get(mid + 1));
      res = max({res, cur, x, y});
      if(cur <= y && cur <= x) {
        if(x >= y) r = mid - 1;
        else l = mid + 1;
      }
      else if(cur <= x) {
        r = mid - 1;
      }
      else if(cur <= y) {
        l = mid + 1;
      }
      else {
        break;
      }
    }
    if(r < n - 1) r++;
    if(l) l--;
  }
  /*else {
    int l = 0, r = n - 1;
    ll need = get(0);
    while((r - l) >= 0) {
      int mid = (r + l) >> 1;
      ll cur = get(mid);
      if(cur >= need && (mid && cur >= get(mid - 1))) l = mid + 1;
      else r = mid - 1;
    }
    if(l) l--;
    res = get(l);
  }*/
  print(res);
}

int main() {
  srand(time(NULL));
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  //freop("");
  int t = 1;
  //read(t);
  for (int i = 1; i <= t; ++i) {
    //write("Case #" + to_string(i) + ": ");
    solve();
  }
  return 0;
}

Compilation message (stderr)

monochrome.cpp: In function 'void freop(std::string)':
monochrome.cpp:73:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |   freopen((s + ".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
monochrome.cpp:74:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |   freopen((s + ".out").c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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