[dynamic planning] change exchange

1.Leetcode Address ：322. Change for - Power button （LeetCode） (leetcode-cn.com)

def coinChange(self, coins, amount):
        """
        :type coins: List[int]
        :type amount: int
        :rtype: int
        """
        dp=[amount+1 for _ in range(amount+1)]
        dp[0]=0
        for i in range(amount+1):
            for coin in coins:
                if i-coin>=0:
                    #if dp[i-coin]==-1:continue
                    dp[i]=min(dp[i],dp[i-coin]+1)
            #dp[i]=-1 if dp[i]==amount+1 else dp[i]
        return -1 if dp[amount]==amount+1 else dp[amount]

2.