#include <bits/stdc++.h>
#define N 2005
#define mod (1000000000 + 7)
using namespace std;
typedef long long ll;
string s;
int n, q, qtd[30][N];
ll dp[30][30][N], 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()
{
ios::sync_with_stdio(false); cin.tie(0);
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]<<"\n";
}
}
Compilation message
mate.cpp: In function 'void solve(int, int)':
mate.cpp:32:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0; i < pos[a].size(); i++)
~~^~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
58 ms |
63992 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
2 |
Runtime error |
60 ms |
64212 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
3 |
Runtime error |
75 ms |
64304 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
4 |
Runtime error |
61 ms |
64308 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
5 |
Runtime error |
61 ms |
64428 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
6 |
Runtime error |
61 ms |
64476 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
7 |
Runtime error |
61 ms |
64492 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
8 |
Runtime error |
60 ms |
64588 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
9 |
Runtime error |
110 ms |
64932 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
10 |
Runtime error |
111 ms |
65040 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |