#include <iostream>
#include <vector>
#include <queue>
#include <fstream>
using namespace std;
typedef long long ll;
typedef pair <ll, ll> pll;
const int N = 2e5 + 10;
const int base = 1e9 + 7;
string s;
int c[2500][2500], res[2500][2500], res0[26][2500], sf[2500][26];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// freopen("in.txt", "r", stdin);
cin >> s;
int n = int(s.size());
for (int i = 0; i < 2500; ++i) {
c[i][0] = c[i][i] = 1;
for (int j = 1; j < i; ++j)
c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % base;
}
for (int i = n - 1; i >= 0; --i)
for (int j = 0; j < 26; j++) {
sf[i][j] = (i + 1 == n ? 0 : sf[i + 1][j]);
sf[i][j] += (s[i] == (j + 'a'));
}
for (int i = 0; i < n; ++i) {
char c1 = s[i];
for (int j = 0; j < 26; ++j)
for (int l = -1; l < i; ++l) {
int v = (c1 - 'a' + 1) + 29 * (j + 1);
int vl = sf[i][j] - ((c1 - 'a') == j);
res[v][l + 1] = (res[v][l + 1] + ((c[i][l + 1] * 1ll * vl) % base)) % base;
}
}
// for (int i = 0; i < n; ++i)
// for (int j = i + 1; j < n; ++j) {
// char c1 = s[i], c2 = s[j];
// int v = (c1 - 'a' + 1) + 29 * (c2 - 'a' + 1);
//
// for (int l = -1; l < i; ++l)
// res[v][l + 1] = (res[v][l + 1] + c[i][l + 1]) % base;
// }
int q;
cin >> q;
while (q--) {
int d;
string t;
cin >> d >> t;
cout << res[(t[0] - 'a' + 1) + 29 * (t[1] - 'a' + 1)][d - 2] << "\n";
}
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
26 ms |
23168 KB |
Output is correct |
2 |
Correct |
24 ms |
22912 KB |
Output is correct |
3 |
Correct |
24 ms |
23040 KB |
Output is correct |
4 |
Correct |
27 ms |
23040 KB |
Output is correct |
5 |
Correct |
55 ms |
24568 KB |
Output is correct |
6 |
Correct |
56 ms |
24696 KB |
Output is correct |
7 |
Correct |
49 ms |
24568 KB |
Output is correct |
8 |
Correct |
46 ms |
24440 KB |
Output is correct |
9 |
Correct |
382 ms |
32312 KB |
Output is correct |
10 |
Correct |
376 ms |
32560 KB |
Output is correct |