Create a copy of the original list and sorting the original list with new create copied list will give us the result if sorting was required to get sorted list or not.
# Python3 code
# to check if list is sorted
# using sort()
# initializing list
list1 = [10, 5, 4, 8, 10]
# printing original list
print ("Original list : " + str(list1))
# using sort() to
# check sorted list
flag = 0
list2 = list1[:]
list2.sort()
if (list2 == list1):
flag = 1
# printing result
if (flag) :
print ("Yes, List is sorted.")
else :
print ("No, List is not sorted.")