Count Ways To Build Good Strings

1class Solution:
2    def countGoodStrings(self, low: int, high: int, zero: int, one: int) -> int:
3        dp = [0] * (high+1)
4        dp[0] = 1
5        ans = 0
6        for i in range(1, high+1):
7            dp[i] = ((dp[i-zero] if i-zero>=0 else 0) + (dp[i-one] if i-one>=0 else 0)) % 1000000007
8            if i >= low:
9                ans = (ans + dp[i]) % 1000000007
10        return ans