Submission #365430

#	Time	Username	Problem	Language	Result	Execution time	Memory
365430		tfg	parentrises (BOI18_parentrises)	C++17	100 / 100	91 ms	110700 KiB

parentrises

#include <iostream>
#include <vector>
#include <chrono>
#include <random>
#include <cassert>

std::mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());

bool good(const std::string &str) {
	int bal = 0;
	for(auto ch : str) {
		bal += ch == '(' ? 1 : -1;
		if(bal < 0) return false;
	}
	return bal == 0;
}

void solve1() {
	int t;
	std::cin >> t;
	while(t--) {
		std::string str;
		std::cin >> str;
		int n = (int) str.size();
		std::vector<int> pos[2];
		std::vector<int> col(n, 3);
		int bst = 0, sum = 0;
		for(int i = 0; i < n; i++) {
			pos[str[i] == '('].push_back(i);
			sum += str[i] == '(' ? 1 : -1;
			bst = std::min(bst, sum);
		}
		int bal = (int) pos[1].size() - (int) pos[0].size();
		if(bst < 0) {
			bal -= bst;
			bst = -bst;
			for(int i = 0; i < 2*bst && i < (int) pos[0].size(); i++) {
				col[pos[0][i]] = i % 2 == 0 ? 1 : 2;
			}
		}
		if(bal > 0) {
			for(int i = 0; i < 2*bal && i < (int) pos[1].size(); i++) {
				col[pos[1][(int) pos[1].size() - i - 1]] = i % 2 == 0 ? 1 : 2;
			}
		}
		
		std::string haha[2];
		for(int i = 0; i < n; i++) {
			if(col[i] & 1) haha[0] += str[i];
			if(col[i] & 2) haha[1] += str[i];
		}
		if(good(haha[0]) && good(haha[1])) {
			for(int i = 0; i < n; i++) {
				char ch;
				if(col[i] == 3) {
					ch = 'G';
				} else if(col[i] == 1) {
					ch = 'R';
				} else {
					ch = 'B';
				}
				std::cout << ch;
			}
			std::cout << '\n';
		} else {
			std::cout << "impossible\n";
		}
	}
}

const int ms = 303;
const int MOD = 1e9 + 7;
long long dp[ms][ms][ms];
long long catalan[ms];
long long wtf[ms];

void solve2() {
	int t;
	std::cin >> t;
	catalan[0] = 1;
	for(int i = 2; i < ms; i += 2) {
		for(int j = 0; j < i; j += 2) {
			catalan[i] = (catalan[i] + catalan[j] * catalan[i-j-2]) % MOD;
		}
	}
	dp[0][0][0] = 1;
	for(int i = 0; i+1 < ms; i++) {
		for(int sum = 0; sum <= i; sum++) {
			for(int mx = 0; mx <= i; mx++) {
				dp[i][sum][mx] %= MOD;
				dp[i+1][sum+1][mx] += dp[i][sum][mx];
				if(sum > 0) {
					dp[i+1][sum-1][mx+1] += dp[i][sum][mx];
				} else if(mx > 0) {
					wtf[i+1] = (dp[i][sum][mx] + wtf[i+1]) % MOD;
					dp[i+1][sum][mx-1] += dp[i][sum][mx];
				}
			}
		}
	}
	wtf[0] = 1;
	while(t--) {
		int n;
		std::cin >> n;
		long long ans = 0;
		for(int i = 0; i <= n; i++) {
			for(int j = 0; i+j <= n; j += 2) {
				ans = (ans + wtf[i] * catalan[j] % MOD * wtf[n-i-j]) % MOD;
			}
		}
		std::cout << ans << '\n';
	}
}

int main() {
	std::ios_base::sync_with_stdio(false); std::cin.tie(NULL);
	int P;
	std::cin >> P;
	if(P == 1) {
		solve1();
	} else {
		solve2();
	}
}

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 6 / 6
• Subtask 4: 28 / 28
• Subtask 5: 6 / 6
• Subtask 6: 16 / 16
• Subtask 7: 28 / 28