title: Chocolate Distribution Problem
signature: function chocolate_distribution_problem(arr, n, m)
test_code: 
  
  -- SOLUTION CODE
  -- ============================================
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  function isCorrect(actual, expected)
      if type(expected) ~= type(actual) then
          return false
      end
      
      if type(expected) == 'table' then
          for k,v_expected in pairs(expected) do
              
              if actual[k] == nil then
                  return false
              end
              local v_actual = actual[k]
              if not isCorrect(v_actual, v_expected) then
                  return false
              end
              actual[k]=nil
          end
      
          if next(actual) then 
              return false
          end
          return true
      else
          return actual == expected
      end
  end
  
  function validateSolution(actual, expected)
      return isCorrect(actual,expected)
  end
  
  function driver(arr, n, m, expected)
      local exec_result;
      local status, error_msg = pcall(function () 
          exec_result=PLACEHOLDER_FN_NAME(arr, n, m) 
      end)
      if status then
          if validateSolution(exec_result,expected) then
              return "PASSED"
          end
          return "FAILED"
      else
          return string.format("ERROR=%s",string.gsub(error_msg,".*:[%d]+: ",""))
      end
  end
      
  function main()
      result = driver({2, 5, 11, 23, 33, 35, 39, 51, 52, 56, 74, 76, 76, 79, 85, 88, 93, 98}, 16, 13, 65)
      print(string.format("TEST-0...%s",result))
  
      result = driver({-94, -94, -88, -84, -74, -70, -56, -50, -48, -42, -34, -24, -18, -14, 0, 4, 4, 16, 16, 30, 36, 42, 52, 56, 72, 74, 76, 84, 88}, 15, 28, -1)
      print(string.format("TEST-1...%s",result))
  
      result = driver({0, 0, 1, 1, 1, 1}, 5, 5, 1)
      print(string.format("TEST-2...%s",result))
  
      result = driver({3, 4, 5, 5, 12, 16, 16, 16, 18, 29, 37, 38, 40, 43, 44, 49, 57, 60, 62, 63, 67, 69, 73, 74, 75, 76, 78, 84, 85, 86, 88, 89, 92}, 25, 18, 57)
      print(string.format("TEST-3...%s",result))
  
      result = driver({-98, -80, -50, -44, -42, -36, -36, -28, -10, -8, -4, -2, 2, 10, 18, 18, 26, 32, 36, 56, 80, 86, 88, 90}, 16, 12, 60)
      print(string.format("TEST-4...%s",result))
  
      result = driver({0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, 13, 14, -1)
      print(string.format("TEST-5...%s",result))
  
      result = driver({13, 15, 62, 65, 87}, 3, 4, -1)
      print(string.format("TEST-6...%s",result))
  
      result = driver({-92, -88, -88, -80, -76, -62, -60, -60, -50, -48, -36, -36, -32, -26, -14, -8, 4, 18, 18, 22, 28, 30, 30, 32, 48, 48, 58, 60, 64, 72, 78, 82, 94}, 31, 17, 90)
      print(string.format("TEST-7...%s",result))
  
      result = driver({0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1}, 9, 6, 1)
      print(string.format("TEST-8...%s",result))
  
      result = driver({17, 23, 25, 38, 40, 53, 58, 73, 77}, 8, 6, 35)
      print(string.format("TEST-9...%s",result))
  
  end
  
  main()
source_py: def chocolate_distribution_problem(arr, n, m):
      if ((m == 0) or (n == 0)):
          return 0
      arr.sort()
      if (n < m):
          return (- 1)
      min_diff = sys.maxsize
      first = 0
      last = 0
      i = 0
      while (((i + m) - 1) < n):
          diff = (arr[((i + m) - 1)] - arr[i])
          if (diff < min_diff):
              min_diff = diff
              first = i
              last = ((i + m) - 1)
          i += 1
      return (arr[last] - arr[first])
source_cpp: int chocolate_distribution_problem(vector<int> arr, int n, int m) {
    if ( m == 0 || n == 0 ) return 0;
    sort(arr.begin(), arr.end());
    if ( n < m ) return - 1;
    int min_diff = INT_MAX;
    int first = 0, last = 0;
    for ( int i = 0;
    i + m - 1 < n;
    i ++ ) {
      int diff = arr [ i + m - 1 ] - arr [ i ];
      if ( diff < min_diff ) {
        min_diff = diff;
        first = i;
        last = i + m - 1;
      }
    }
    return ( arr [ last ] - arr [ first ] );
  }