code: def subset_sum(x, R):
      
      b = [False] * (R + 1)
      b[0] = True
      for xi in x:
          for s in range(R, xi - 1, -1):
              b[s] |= b[s - xi]
      return b[R]
docs: Subsetsum
  
      :param x: table of non negative values
      :param R: target value
      :returns bool: True if a subset of x sums to R
      :complexity: O(n*R)