Submission #757290

#	Time	Username	Problem	Language	Result	Execution time	Memory
757290		SanguineChameleon	Linear Garden (IOI08_linear_garden)	C++17	100 / 100	30 ms	9120 KiB

linear_garden

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

void just_do_it();

int main() {
	#ifdef KAMIRULEZ
		freopen("kamirulez.inp", "r", stdin);
		freopen("kamirulez.out", "w", stdout);
	#endif
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	just_do_it();
	return 0;
}

const int maxn = 1e6 + 20;
int a[maxn];
int pw[maxn];

void just_do_it() {
	int n, mod;
	cin >> n >> mod;
	pw[0] = 1;
	for (int i = 1; i <= n; i++) {
		pw[i] = pw[i - 1] * 2 % mod;
	}
	a[0] = -1;
	for (int i = 1; i <= n; i++) {
		char c;
		cin >> c;
		if (c == 'L') {
			a[i] = 0;
		}
		if (c == 'P') {
			a[i] = 1;
		}
	}
	int res = 1;
	int cur = -1;
	for (int i = 1; i <= n; i++) {
		if (a[i] == 1) {
			if (a[i - 1] == 0) {
				if (cur != 0) {
					res += pw[(n - i) / 2];
					res %= mod;
				}
			}
			else {
				if (cur != 0) {
					res += pw[(n - i + 1) / 2] + mod - 1;
					res %= mod;
				}
				if (cur != 1) {
					res += pw[(n - i) / 2] + mod - 1;
					res %= mod;
				}
				res += 1;
				res %= mod;
			}
		}
		cur = (a[i - 1] == a[i] ? a[i] : cur);
	}
	cout << res;
}

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