message: Update arranging-coins.py
diff: @@ -21,12 +21,14 @@ class Solution2(object):
  :type n: int
  :rtype: int
  """
  + def check(mid, n):
  + return mid*(mid+1) <= 2*n
  +
  left, right = 1, n
  while left <= right:
  - mid = left + (right - left) / 2
  - if 2 * n < mid * (mid+1):
  + mid = left + (right-left)//2
  + if not check(mid, n):
  right = mid-1
  else:
  left = mid+1
  - return left - 1
  -
  + return right
  