#include <bits/stdc++.h>
using namespace std;
#define mod (1000000000 + 7)
#define N 2005
typedef long long ll;
string s;
int q, n, qtd[30][N];
ll dp[N][30][30], ch[N][N];
vector<int> pos[30];
ll choose(int a, int b) {
if (a == b || b == 0)
return 1;
if (b == 1)
return a;
if (b > a)
return 0;
if (ch[a][b] != -1)
return ch[a][b];
return ch[a][b] = (choose(a - 1, b - 1) + choose(a - 1, b)) % mod;
}
void solve(int a, int b) {
for (int len = 1; len <= n; len++) {
for (int i = 0; i < pos[a].size(); i++) {
int x = pos[a][i];
dp[len][a][b] += ((ll)qtd[b][x + 1] * choose(x - 1, len - 2)) % mod;
dp[len][a][b] %= mod;
}
}
}
int main() {
cin >> s;
n = s.size();
for (int c = 0; c < 30; c++) {
for (int i = n; i >= 1; i--) {
qtd[c][i] = qtd[c][i + 1] + (s[i - 1] - 'a' == c);
}
}
for (int i = 1; i <= n; i++)
pos[s[i - 1] - 'a'].push_back(i);
memset(ch, -1, sizeof(ch));
for (int a = 0; a < 30; a++) {
for (int b = 0; b < 30; b++) {
solve(a, b);
}
}
cin >> q;
while (q--) {
int l;
string aux;
cin >> l >> aux;
int a = aux[0] - 'a', b = aux[1] - 'a';
cout << dp[l][a][b] << endl;
}
}
Compilation message
mate.cpp: In function 'void solve(int, int)':
mate.cpp:26:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
26 | for (int i = 0; i < pos[a].size(); i++) {
| ~~^~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
43 ms |
33628 KB |
Output is correct |
2 |
Correct |
29 ms |
33628 KB |
Output is correct |
3 |
Correct |
34 ms |
33696 KB |
Output is correct |
4 |
Correct |
54 ms |
33824 KB |
Output is correct |
5 |
Correct |
189 ms |
35152 KB |
Output is correct |
6 |
Correct |
213 ms |
35508 KB |
Output is correct |
7 |
Correct |
168 ms |
35156 KB |
Output is correct |
8 |
Correct |
149 ms |
34936 KB |
Output is correct |
9 |
Runtime error |
41 ms |
68084 KB |
Execution killed with signal 11 |
10 |
Runtime error |
39 ms |
67924 KB |
Execution killed with signal 11 |