Submission #1094150

#	Time	Username	Problem	Language	Result	Execution time	Memory
1094150		thangdz2k7	Monochrome Points (JOI20_monochrome)	C++17	100 / 100	14 ms	4624 KiB

monochrome

// author : thembululquaUwU
// 3.9.2024

#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define endl '\n'

using namespace std;
using ll = long long;
using ii = pair <int, int>;
using vi = vector <int>;

const int N = 4e5 + 5;
const int mod = 1e9 + 7;

void maxl(auto &a, auto b) {a = max(a, b);}
void minl(auto &a, auto b) {a = min(a, b);}

int n;
string s;

void solve(){
    cin >> n;
    cin >> s;
    vi black, white;
    for (int i = 0; i < 2 * n; ++ i) if (s[i] == 'B') black.pb(i); else white.pb(i);
    vector <ll> 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;
    for (int i = 0; i < n; ++ i){
        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;
    for (int i = 0; i < n; ++ i){
        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]);
    }

    #define all(x) (x).begin(), (x).end()
    #define rall(x) (x).rbegin(), (x).rend()
    #define fd(sr, x) (lower_bound(sr.begin(), sr.end(), x) - sr.begin())
    #define uq(sr) (sr).erase(unique(all((sr))), (sr).end())
    #define szv(v) (int((v).size()))

    partial_sum(all(pref), pref.begin());
    cout << (*max_element(all(pref)) - n) / 2;
}

int main(){
    if (fopen("pqh.inp", "r")){
        freopen("pqh.inp", "r", stdin);
        freopen("pqh.out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int t = 1; // cin >> t;
    while (t --) solve();
    return 0;
}

Compilation message (stderr)

monochrome.cpp:18:11: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   18 | void maxl(auto &a, auto b) {a = max(a, b);}
      |           ^~~~
monochrome.cpp:18:20: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   18 | void maxl(auto &a, auto b) {a = max(a, b);}
      |                    ^~~~
monochrome.cpp:19:11: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   19 | void minl(auto &a, auto b) {a = min(a, b);}
      |           ^~~~
monochrome.cpp:19:20: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
   19 | void minl(auto &a, auto b) {a = min(a, b);}
      |                    ^~~~
monochrome.cpp: In function 'int main()':
monochrome.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen("pqh.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
monochrome.cpp:74:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |         freopen("pqh.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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