title: Find the minimum sum obtained from summing each integers from a list
body: <p>I'm learning python and I'm training myself on different exercises. For one of them I have to find the minimum sums of the product of two numbers from a list. For this I had the idea of making a list and sort it in order and to create a second list where I'll sort it in reverse order then I will make the product of the first element of each list and sum them together. </p>
  
  <p>Here's a little example:</p>
  
  <pre><code>list[5, 4, 2, 3]
  
  list_sorted = [2, 3]
  list_sorted_rev = [5, 4]
  
  expectation = 22
  
  calcul made: 5 * 2 + 3 * 4
  </code></pre>
  
  <p>But I have a problem, when I do that in a loop, my loop iterate through the second list with the first value of my first list and then it goes to the second value of my first list. </p>
  
  <p>Here's the code I've done. </p>
  
  <pre><code>def min_sum(arr):
      my_list = []
      my_rev = []
      srt = sorted(arr)
      rev = sorted(arr, reverse=True)
      rng = len(arr) / 2
      res = 0
  
      for i in range(0, int(rng)):
          my_list.append(srt[i])
          my_rev.append(rev[i])
      for i in my_rev:
          for j in my_list:
              res += i * j
      print(res)
  </code></pre>