how t find second greatest digit in a number ? Python - python-2.7

Question

The Program must take a number and print the second largest digit in the number.
i have tried this ==>
a=raw_input("Please enter the nummber =")
l=list()
for i in a:
l.append(int(i))
great=0
for i in range(0,len(l)):
for j in l:
if l[i]>j:
if l[i]>great:
great=l[i]
print great
for i in range(20):
great-=1
for j in l:
if j==great:
print "Second largest number is ",j
break
But this gave Output
Please enter the nummber =1459
9
Second largest number is 5
Second largest number is 4
Second largest number is 1

Answer 1

this easily accomplished using the build-in function of python map and sorted
once you have the number from raw_input you can do this
>>> a
'1459'
>>> ordnum = sorted(map(int,a),reverse=True)
>>> ordnum[1]
5
>>> ordnum
[9, 5, 4, 1]
>>>
first with map convert every digit to a number, and result is passed to sorted that order them in ascending order by default, but with the reverse key-word argument the orden is reversed, then you get a list with the digit in order so the second elements is the desire digit.
Or as you already do the map part, you can do the sort part directly to the list
>>> l
[1, 4, 5, 9]
>>> l.sort(reverse=True)
>>> l
[9, 5, 4, 1]
>>>
to the same efect.
The problem with your code is that you don't break the first for-loop, only the second, to break both you can do as #cjahangir show, or make that into a function that return when find it like this
def second_great(great,num):
for i in range(10):
great -= 1
for j in num:
if j == great:
return j
and call it as
print great
print "Second largest number is ", second_great(great,l)
as pointed out by #Blckknght, the conversion to int is unneeded in this case because the digit are order correctly when handled individually, also you can use set to remove repetitions in any of the versions.
>>> b="1459934"
>>> sorted(b,reverse=True)
['9', '9', '5', '4', '4', '3', '1']
>>> sorted(set(b),reverse=True)
['9', '5', '4', '3', '1']
>>> sorted(map(int,set(b)),reverse=True)
[9, 5, 4, 3, 1]
>>>

Answer 2

I think this will work:
print great
flag = 0
for i in range(20):
great-=1
for j in l:
if j==great:
print "Second largest number is ",j
flag = 1
break
if flag:
break