Submission #83307

#	Time	Username	Problem	Language	Result	Execution time	Memory
83307		fredbr	Mate (COCI18_mate)	C++17	80 / 100	2072 ms	42312 KiB

mate

#include <bits/stdc++.h>

using namespace std;

const int maxm = 30;
const int maxn = 2010;

typedef long long ll;

const ll mod = 1000000007;

ll dp[maxm][maxm][maxn];
ll pchoose[maxn][maxn];

ll choose(ll n, ll k)
{
	if (pchoose[n][k] >= 0) return pchoose[n][k];

	return pchoose[n][k] = (choose(n-1, k) + choose(n-1, k-1)) % mod;
}

void init()
{
	memset(pchoose, -1, maxn*maxn*8);
	
	for (int i = 0; i < maxn; i++) {

		pchoose[i][0] = 1;
		pchoose[i][i] = 1;
	}
}

int main()
{	
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	
	string s;
	cin >> s;

	int n = s.size();

	init();

	for (int i = 0; i < n-1; i++) {

		for (int j = i+1; j < n; j++) {

			for (int k = 0; k <= i; k++) {

				dp[s[i]-'a'][s[j]-'a'][k+2] += choose(i, k);
				dp[s[i]-'a'][s[j]-'a'][k+2] %= mod;
			}
		}
	}

	int q;
	cin >> q;

	while (q--) {

		int num;
		char a, b;

		cin >> num >> a >> b;

		cout << dp[a-'a'][b-'a'][num] << "\n";
	}

	return 0;
}

• Subtask 1: 80 / 100