Submission #341450

#	Time	Username	Problem	Language	Result	Execution time	Memory
341450		ryansee	Monochrome Points (JOI20_monochrome)	C++14	4 / 100	1 ms	492 KiB

monochrome

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

#define FAST ios_base::sync_with_stdio(false); cin.tie(0);
#define pb push_back
#define eb emplace_back
#define ins insert
#define f first
#define s second
#define cbr cerr<<"hi\n"
#define mmst(x, v) memset((x), v, sizeof ((x)))
#define siz(x) ll(x.size())
#define all(x) (x).begin(), (x).end()
#define lbd(x,y) (lower_bound(all(x),y)-x.begin())
#define ubd(x,y) (upper_bound(all(x),y)-x.begin())
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());    //can be used by calling rng() or shuffle(A, A+n, rng)
inline long long rand(long long x, long long y) { return rng() % (y+1-x) + x; } //inclusivesss
string inline to_string(char c) {string s(1,c);return s;} template<typename T> inline T gcd(T a,T b){ return a==0?llabs(b):gcd(b%a,a); }

using ll=long long; 
using ld=long double;
#define FOR(i,s,e) for(ll i=s;i<=ll(e);++i)
#define DEC(i,s,e) for(ll i=s;i>=ll(e);--i)
using pi=pair<ll,ll>; using spi=pair<ll,pi>; using dpi=pair<pi,pi>; 

long long LLINF = 1e18;
int INF = 1e9+1e6;
#define MAXN (400006)
ll n, ans;
deque<char> A;
ll nC2(ll n) { return n * (n-1) / 2; }
ll lol() {
	ll ans = 0, grad = 0;
	FOR(i,0,n-1) {
		if(A[i] == A[n+i]) {
			if(A[i] == 'W') {
				-- grad;
			} else if(A[n+i] == 'B') {
				++ grad;
			}
		}
		ans += abs(grad);
	}
	assert(grad == 0);
	return nC2(n) - ans;
}
int main() {
	FAST
	cin>>n;
	A.resize(n*2);
	for(auto&i:A)cin>>i;
	FOR(i,0,n*2) {
		if(i == n*2 || A[0] == A[n-1]) {
			ans = max(ans, lol());
			break;
		}
		A.eb(A[0]), A.pop_front();
	}
	cout<<ans<<'\n';
}

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