leetcode-master/problems/0518.零钱兑换II.md

// 计算有多少种方式 // 完全背包 for循环的顺序啊，先是哪个for 后是哪个for定不下来

排列

class Solution {
public:
    int change(int amount, vector<int>& coins) {
        int dp[50001] = {0};
        dp[0] = 1;
        for (int i = 0; i <= amount; i++) {
            for (int j = 0; j < coins.size(); j++) { // 这是组合把？？？
                if (i - coins[j] >= 0) dp[i] += dp[i - coins[j]];
            }
            for (int j = 0; j <= amount; j++) {
                cout << dp[j] << " ";
            }
            cout << endl;
        }
        return dp[amount];
    }
};

这个才是组合，本题的题解，

class Solution {
public:
    int change(int amount, vector<int>& coins) {
        int dp[50001] = {0};
        dp[0] = 1;
        for (int i = 0; i < coins.size(); i++) { // 一个钱币只在序列里出现一次
            for (int j = 0; j <= amount; j++) {
                if (j - coins[i] >= 0) dp[j] += dp[j - coins[i]];
            }
        }
        return dp[amount];
    }
};