在一組中找出基數C的所有可能的子集0-N

Question

如何獲取一組大小爲N的數字並打印給定基數的所有可能子集？

例如[0 1 2]，2 - > [0 1]，[0 2]，[1,2]

我找不到代碼，而且花了一些時間寫出來，所以我想它可能是有幫助:)

Answer 1

您可以使用此功能：

void printSets(int N, int Cardinality) 
{ 
     std::vector<int> nums; 
     helper(nums, 0, 0, N, Cardinality);  
} 

使用輔助函數：

void helper(std::vector<int> &nums, int size, int index, int max, int cardinality) 
{ 
     if (size == cardinality) //SET IS READY TO PRINT (base case)         
     { 
      for (int k = 0; k < cardinality; ++k) 
        std::cout<< nums[k] << " "; 
      std::cout << std::endl; 
      return; 
     } 
     for (int i = index; i < max+1; ++i) //WE LOOP THROUGH THE SPACES LEFT    
     { 
      nums.push_back(i); 
      helper(nums, size+1, i+1, max, cardinality); //WE NEST AS MANY LOOPS AS THE CARDINALITY 
      nums.pop_back(); 
     } 
}