Submission #1141068

#	Time	Username	Problem	Language	Result	Execution time	Memory
1141068		the_coding_pooh	Monochrome Points (JOI20_monochrome)	C++20	25 / 100	2 ms	328 KiB

monochrome

#include <bits/stdc++.h>
#define uwu return 0;

using namespace std;

#define fs first
#define sc second

const int SIZE = 2e5 + 5, TL = 1900;

string S;

int pos[2][SIZE], seg[SIZE];

int BITree[SIZE];

void modify(int pos, int val){
    for (; pos < SIZE; pos += (pos & - pos)){
        BITree[pos] += val;
    }
    return;
}

int query(int pos){
    int ret = 0;
    for (; pos; pos -= (pos & - pos)){
        ret += BITree[pos];
    }
    return ret;
}

#define is_W(i) (S[(i + x) % (2 * N)] == 'W') 

long long eval(int x, int N){
    for (int i = 0; i < 2 * N; i++){
        BITree[i] = 0;
    }
    int ptr[2] = {0, 0};
    for (int i = N; i < S.size(); i++){
        pos[is_W(i)][ptr[is_W(i)]++] = i;
    }
    ptr[0] = 0, ptr[1] = 0;
    long long ans = 0;
    for (int i = 0; i < N; i++){
        ans += query(pos[1 - is_W(i)][ptr[1 - is_W(i)]]);
        modify(pos[1 - is_W(i)][ptr[1 - is_W(i)]++], 1);
    }
    return ans;
}

mt19937 rng(time(0));

int main(){
    cin.tie(0), ios::sync_with_stdio(0);
    int N;
    cin >> N >> S;
    long long ans = 0;
    auto ck = clock();
    for (; int(clock() - ck) < TL;){
        ans = max(ans, eval(rng() % (2 * N), N));
    }
    cout << ans << '\n';
    uwu
}

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