python LeetCode 377. Combination Sum IV

求多少种一般是动态规划 要具体写出各种的情况一般是dfs
本题类似于换硬币

class Solution:
    def combinationSum4(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        
        dp=[0]*(target+1)
        dp[0]=1
        for i in range(1,target+1):
            for n in nums:
                if n<=i: dp[i]+=dp[i-n]
        return dp[target]