DP problems

322. Coin Change

class Solution:
    def coinChange(self, coins: List[int], amount: int) -> int:
        if not coins:return -1
        dp = [float('inf')]*(amount+1)
        dp[0] = 0
        coins= set(coins)
        for i in range(1, amount+1):
            for c in coins:
                if i-c>=0:
                    dp[i] = min(dp[i], 1+dp[i-c])
        return dp[-1] if dp[-1]!=float('inf') else -1