public int uniquePaths(int m, int n) {
        int[][] cache = new int[m][n];
        
        for(int i = 0; i < m; i++){
            for(int j = 0; j < n; j++){
                if(i == 0 || j == 0) 
                    cache[i][j] = 1;
                else
                    cache[i][j] = cache[i-1][j] + cache[i][j-1];
            }
        }
        return cache[m-1][n-1];
    }
}