public long count(int N, int M, int K)
{
int i, j, k;
int len = N - M + 1;
long res = 0;
if (K == 0)
{
return((long)(Math.Pow(26, N) + 1e-9));
}
long[] mul = new long[len + 1];
if (len >= K)
{
mul[K] = 1;
}
for (i = K + 1; i <= len; i++)
{
long now = 0;
for (j = 0; j < i; j++)
{
now -= c(i, j) * mul[j];
}
mul[i] = now + 1;
}
for (i = 0; i < (1 << len); i++)
{
int count = 0;
Unionfind uni = new Unionfind(N);
for (j = 0; j < len; j++)
{
if ((i >> j) % 2 == 1)
{
count++;
for (k = 0; k <= (M - 1) / 2; k++)
{
uni.connect(j + k, j + M - k - 1);
}
}
}
if (K > count)
{
continue;
}
long now = 1;
for (j = 0; j < N; j++)
{
if (uni.root(j) == j)
{
now *= 26;
}
}
res += now * mul[count];
}
return(res);
}
public long count(int N, int M, int K)
{
int i, j, k;
int len = N - M + 1;
long res = 0;
if (K == 0) return (long)(Math.Pow(26, N) + 1e-9);
long[] mul = new long[len + 1];
if (len >= K) mul[K] = 1;
for (i = K + 1; i <= len; i++)
{
long now = 0;
for (j = 0; j < i; j++)
{
now -= c(i, j) * mul[j];
}
mul[i] = now + 1;
}
for (i = 0; i < (1 << len); i++)
{
int count = 0;
Unionfind uni = new Unionfind(N);
for (j = 0; j < len; j++)
{
if ((i >> j) % 2 == 1)
{
count++;
for (k = 0; k <= (M - 1) / 2; k++)
{
uni.connect(j + k, j + M - k - 1);
}
}
}
if (K > count) continue;
long now = 1;
for (j = 0; j < N; j++)
{
if (uni.root(j) == j)
{
now *= 26;
}
}
res += now * mul[count];
}
return res;
}