| author | Christian Urban <urbanc@in.tum.de> |
| Wed, 28 Nov 2018 17:13:40 +0000 | |
| changeset 219 | 44161f2c3226 |
| parent 156 | cc6d036401f4 |
| permissions | -rw-r--r-- |
| 155 | 1 |
#!/usr/bin/env python |
2 |
import re |
|
3 |
import sys |
|
4 |
||
5 |
# case of catastrophic backtracking in Python |
|
6 |
# |
|
| 156 | 7 |
# regex: (a*)*b |
8 |
# strings: aa...a |
|
| 155 | 9 |
# |
10 |
# call with timing as: |
|
11 |
# |
|
12 |
# > time ./catastrophic.py 20 |
|
13 |
||
14 |
# counter n given on the command line |
|
15 |
cn = sys.argv[1] |
|
16 |
||
| 156 | 17 |
# calling the matching function |
18 |
s = ("a" * int(cn))
|
|
19 |
m = re.match('(a*)*b' , s)
|
|
| 155 | 20 |
|
| 156 | 21 |
print s |