【leetcode刷题】T170-组合总和 Ⅳ

示例:
nums = [1, 2, 3]
target = 4
所有可能的组合为：
(1, 1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 3)
(2, 1, 1)
(2, 2)
(3, 1)
请注意，顺序不同的序列被视作不同的组合。
因此输出为 7。

class Solution(object):
    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 i >= n:
                    dp[i] += dp[i - n]
        return dp[-1]

class Solution {
public:
    int combinationSum4(vector<int>& nums, int target) {
        vector<double> dp(target+1, 0);
        dp[0] = 1;
        for(int i=1; i <= target; i++){
            for(auto n: nums){
                if(i >= n)
                    dp[i] += dp[i - n];
            }
        }
        return dp.back();
    }
};