未过样例的DP，求助。

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
typedef long long ll;
int n, K;
bool a[55][55];
ll dp[55][55][4][2] = {{{{0}}}};//0朝下，1朝右 
void init() {
	memset(a, 0, sizeof a);
	memset(dp, 0, sizeof  dp);
	cin >> n >> K;
	char c;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= n; j++) {	
			cin >> c;
			a[i][j] = (c == '.');
		}
}
void solve () {
	init();
	dp[1][1][0][1] = dp[1][1][0][0] = 1;
	for (int i = 2; i <= n && a[i][1]; i++)
		dp[i][1][0][0] = 1, dp[i][1][1][1] = 1;
	for (int i = 2; i <= n && a[1][i]; i++)
		dp[1][i][0][1] = 1, dp[1][i][1][0] = 1; 
	for (int i = 2; i <= n; i++)
		for (int j = 2; j <= n; j++) 
			for (int k = 1; k <= K; k++) {
				if (!a[i][j])continue;
				dp[i][j][k][1] = dp[i][j - 1][k][1];
				dp[i][j][k][0] = dp[i - 1][j][k][0];
				if (k > 0) {
					dp[i][j][k][1] += dp[i - 1][j][k - 1][0];
					dp[i][j][k][0] += dp[i][j - 1][k - 1][1];
				}
		//		printf("%d %d %d %d %d\n", i, j, k, dp[i][j][k][0], dp[i][j][k][1]);
			}	
	ll ans = 0;
	for (int i = 1; i <= K; i++)
		ans += dp[n][n][i][0] + dp[n][n][i][1];
	cout << ans << endl;
}

int main() {
	int T;
	cin >> T;
	while(T--)
		solve();	
	return 0;
}