Find gaps in a sequence of Strings

Question

I have got a sequence of strings - 0000001, 0000002, 0000003.... upto 2 million. They are not contiguous. Meaning there are gaps. Say after 0000003 the next str

Answer 1

I would suggest take it int rather than string for processing and then making it a string again in output

j=0
n=2000000
#create a list of int number from your string
foo = [i for i in range(n)]
#creating gaps
foo.remove(1)
foo.remove(50)
while jj:
            print '%07d'%j
            j+=1
        j+=1