leetcode377 Combination Sum IV

思路：

dp。

实现：

 class Solution
 {
 public:
     int combinationSum4(vector<int>& nums, int target)
     {
         if (nums.empty()) return target == ;
         vector<int> dp(target + , );
         dp[] = ;
         vector<int> tmp(nums.begin(), nums.end());
         sort(tmp.begin(), tmp.end());
         int n = tmp.size();
         for (int i = ; i <= target; i++)
         {
             for (int j = ; tmp[j] <= i && j < n; j++)
             {
                 dp[i] += dp[i - tmp[j]];
             }
         }
         return dp[target];
     }
 };