Shared code

#include <bits/stdc++.h> 
using namespace std;  

typedef long long ll;  
typedef pair<int, int> ii;  

const int INF = 1e9;  
const ll LINF = 1e18;  

const int N = 1e3 + 5;  
const int MOD = 1e9 + 7;  

int n;  
string grid[N];  

bool inSide(int x, int y) {
	return (1 <= x && x <= n && 1 <= y && y <= n);  
}

int memo[N][N];  

int dp(int x, int y) {
	if (!inSide(x, y)) return 0;   
	if (grid[x][y] == '*') return 0;  
	
	if (x == 1 && y == 1) return (grid[1][1] == '.');  

	int& ans = memo[x][y];  
	if (ans != -1) return ans;  

	ans = dp(x - 1, y) + dp(x, y - 1);  
	ans %= MOD;   
	
	return ans;  
}

int main() {
	ios::sync_with_stdio(0); cin.tie(0);  	
	cin >> n;   

	for (int i = 1; i <= n; i++) {
		cin >> grid[i];  
		grid[i] = ' ' + grid[i]; 
	}

	memset(memo, -1, sizeof memo);  

	cout << dp(n, n) << '\n'; 
}