518

class Solution {
public:
    int change(int amount, vector<int>& coins) {
        vector<int> dp(amount+1);
        dp[0] = 1;

        for(int coin:coins){
            for(int i=1; i<=amount; i++)
                if(i>=coin)
                    dp[i] += dp[i-coin];
        }
        return dp[amount];
    }
};