python & C++ LeetCode 322 动态规划

python代码：

class Solution:
    def coinChange(self, coins: List[int], amount: int) -> int:
        Max = amount + 1
        dp = [Max for _ in range(Max)]
        dp[0] = 0
        for i in range(1, Max):
            for j in range(len(coins)):
                if coins[j] <= i:
                    dp[i] = min(dp[i], dp[i - coins[j]] + 1)
        
        return dp[amount] if dp[amount] < Max else -1

C++代码：

class Solution {
public:
    int coinChange(vector& coins, int amount) {
        vector dp(amount + 1, amount + 1);  // 数组大小为 amount + 1，初始值也为 amount + 1
        dp[0] = 0; // base case
        for (int i = 0; i < dp.size(); i++) {
            for (int coin : coins) {  // 内层 for 在求所有子问题 + 1 的最小值
                if (i - coin < 0) continue;  // 子问题无解，跳过
                dp[i] = min(dp[i], 1 + dp[i - coin]);
            }
        }
        return (dp[amount] == amount + 1) ? -1 : dp[amount];
    }
}