Coin Change II Python Solution with Tests

lcpy gen -n 518   # by problem number
lcpy gen -s coin_change_ii   # by problem name

Input: amount = 5, coins = [1,2,5]
Output: 4

Input: amount = 3, coins = [2]
Output: 0

Input: amount = 10, coins = [10]
Output: 1

class Solution:
    # Time: O(n * amount)
    # Space: O(amount)
    def change(self, amount: int, coins: list[int]) -> int:
        # dp[a] = number of combinations summing to a
        dp = [0] * (amount + 1)
        dp[0] = 1
        for coin in coins:
            for a in range(coin, amount + 1):
                dp[a] += dp[a - coin]
        return dp[amount]