public static Modular Pow(Modular a, int n)
{
switch (n)
{
case 0:
return(1);
case 1:
return(a);
default:
var p = Pow(a, n / 2);
return(p * p * Pow(a, n % 2));
}
}
public void Solve()
{
@in(out H, out W, out K);
int fall = 0;
int p = (int)Math.Pow(2, W - 1);
// 全探索
for (int i = 0; i < p; i++)
{
bool invalidate = false;
var n = i;
bool before = false;
for (int j = 0; j < W - 1; j++)
{
int bit = n % 2;
n = n >> 1;
if (bit != 0 && before)
{
invalidate = true;
break;
}
before = bit != 0;
}
if (invalidate)
{
continue;
}
fall++;
}
Modular[][] dp = new Modular[H + 1][];
dp[0] = new Modular[W];
dp[0][0] = 1;
for (int i = 1; i < W; i++)
{
dp[0][i] = 0;
}
for (int i = 1; i <= H; i++)
{
dp[i] = new Modular[W];
for (int j = 0; j < W; j++)
{
dp[i][j] = 0;
}
for (int j = 0; j < W; j++)
{
dp[i][j] = dp[i - 1][j];
if (j > 0)
{
dp[i][j] = dp[i][j] + dp[i - 1][j - 1];
}
if (j < W - 1)
{
dp[i][j] = dp[i][j] + dp[i - 1][j + 1];
}
}
}
Console.WriteLine((int)dp[H][K - 1]);
}
