打卡题目：leetcode第322题，零钱兑换
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    【代码】

    1. class Solution:
    2.     def coinChange(self, coins: List[int], amount: int) -> int:
    3.         dp = [amount + 1] * (amount + 1)
    4.         dp[0] = 0
    5.         # 对于每个coin，dp[i] = min(dp[i], dp[i-coin]+1)
    6.         for i in range(1, amount + 1):
    7.             for coin in coins:
    8.                 if i >= coin:
    9.                     dp[i] = min(dp[i], dp[i-coin]+1)
    10.         return dp[-1] if dp[-1] != amount+1 else -1