1621. Number of Sets of K Non-Overlapping Line Segments

class Solution:
    def numberOfSets(self, n: int, k: int) -> int:
        mod = 10**9 + 7
        f = [[0] * (k + 1) for _ in range(n + 1)]
        g = [[0] * (k + 1) for _ in range(n + 1)]
        f[1][0] = 1
        for i in range(2, n + 1):
            for j in range(k + 1):
                f[i][j] = (f[i - 1][j] + g[i - 1][j]) % mod
                g[i][j] = g[i - 1][j]
                if j:
                    g[i][j] += f[i - 1][j - 1]
                    g[i][j] %= mod
                    g[i][j] += g[i - 1][j - 1]
                    g[i][j] %= mod
        return (f[-1][-1] + g[-1][-1]) % mod