Submission #950738

#	Time	Username	Problem	Language	Result	Execution time	Memory
950738		marvinthang	Monochrome Points (JOI20_monochrome)	C++17	100 / 100	14 ms	4584 KiB

monochrome

/*************************************
*    author: marvinthang             *
*    created: 20.03.2024 21:31:00    *
*************************************/

#include <bits/stdc++.h>

using namespace std;

#define                  fi  first
#define                  se  second
#define                left  ___left
#define               right  ___right
#define                TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define             MASK(i)  (1LL << (i))
#define           BIT(x, i)  ((x) >> (i) & 1)
#define  __builtin_popcount  __builtin_popcountll
#define              ALL(v)  (v).begin(), (v).end()
#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define          REPD(i, n)  for (int i = (n); i-- > 0; )
#define        FOR(i, a, b)  for (int i = (a), _b = (b); i < _b; ++i) 
#define       FORD(i, b, a)  for (int i = (b), _a = (a); --i >= _a; ) 
#define       FORE(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define      FORDE(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i) 
#define        scan_op(...)  istream & operator >> (istream &in, __VA_ARGS__ &u)
#define       print_op(...)  ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
    #include "debug.h"
#else
    #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
    #define DB(...) 23
    #define db(...) 23
    #define debug(...) 23
#endif

template <class U, class V> scan_op(pair <U, V>)  { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>)  { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>)  { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")";  else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }

// end of template

void process(void) {
    int n; string s; cin >> n >> s;
    vector <int> black, white;
    REP(i, n + n) (s[i] == 'B' ? black : white).push_back(i);
    vector <long long> pref(n);
    auto update = [&] (int l, int r, int x) {
        if (l >= r) return;
        if (l < 0) l += n, r += n;
        if (r > n) r -= n;
        pref[l] += x;
        if (r < n) pref[r] -= x;
        if (l >= r) pref[0] += x;
    };
    int j = 0, k = 0, l = 0;
    REP(i, n) {
        while (j < n && white[j] - black[i] <= -n) ++j;
        while (k < n && white[k] - black[i] <= 0) ++k;
        while (l < n && white[l] - black[i] <= n) ++l;
        update(-i, j - i, n + n - black[i]);
        update(j - i, k - i, black[i]);
        update(k - i, l - i, -black[i]);
        update(l - i, n - i, n + n + black[i]);
    }
    j = k = l = -1;
    REP(i, n) {
        while (j + 1 < n && white[i] - black[j + 1] > n) ++j;
        while (k + 1 < n && white[i] - black[k + 1] > 0) ++k;
        while (l + 1 < n && white[i] - black[l + 1] > -n) ++l;
        update(i - n + 1, i - l, white[i]);
        update(i - l, i - k, -white[i]);
        update(i - k, i - j, white[i]);
        update(i - j, i + 1, -white[i]);
    }
    partial_sum(ALL(pref), pref.begin());
    cout << (*max_element(ALL(pref)) - n) / 2 << '\n';
}

int main(void) {
    ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
    file("JOI20_monochrome");
    // int t; cin >> t; while (t--)
    process();
    // cerr << "Time elapsed: " << TIME << " s.\n";
    return (0^0);
}

Compilation message (stderr)

monochrome.cpp: In function 'int main()':
monochrome.cpp:30:61: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
monochrome.cpp:84:5: note: in expansion of macro 'file'
   84 |     file("JOI20_monochrome");
      |     ^~~~
monochrome.cpp:30:94: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
monochrome.cpp:84:5: note: in expansion of macro 'file'
   84 |     file("JOI20_monochrome");
      |     ^~~~

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