Question

TLE always happen in SBANK SPOJ using python. In order to solve it, i have to sort dict(), though dict() has huge number of KEYS(maximum–100000). Use sorted() function in my code takes no effect. Is there any fast solution? Thanks for your help.

My code below:

for j in range(n): # n is the number of keys
        account = sys.stdin.readline().rstrip()
        dic.setdefault(account, 0)
        dic[account] += 1
sorted(dic) # **this sort take a lot of time**

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EDIT1:According to Justin Peel’s tips, i update my code below, but return still TLE. How can i do?

import sys
import psyco # import psyco module to speed up
psyco.full()
nCase = int(sys.stdin.readline().split()[0])
for i in range(nCase):
    n = int(sys.stdin.readline().split()[0])
    dic = dict()
    lst = list()
    for j in range(n):
        account = sys.stdin.readline().rstrip()
        dic.setdefault(account, 0)
        dic[account] += 1
    sys.stdin.readline()
    lst = dic.keys() # store keys in list
    lst.sort()
    for account in lst:
        sys.stdout.write('%s %s\n' % (account, dic[account]))

Answer 1

I was able to solve this problem. Here are some tips:

1. Use Python 2.5. It is much faster than Python 3.2 which is the other option available on SPOJ with Python. Only one person has been able to get a fast enough solution using Python 3.2
2. Just use a basic dict for counting. You can get by with the defaultdict from the collections module too, but the basic dict was faster for me.
3. Sort only the keys of the dict, not the key-item pairs. Forming the key-item pairs takes far too long. Also, use keys = mydict.keys(); keys.sort() because it is the fastest way to go about it.
4. Use psyco (pretty much always with SPOJ problems in Python)
5. Learn the fastest ways to do input and output in Python. Hint: it isn’t iterating over every line of input for example.
6. Try submitting after you’ve added each part (getting input, counting, doing output) to see where you are with time. This is a very valuable thing to do on SPOJ. The SPOJ computer running your code is quite likely much slower than your current computer and it can be hard to determine based on your own computer’s running time of the code if it will be fast enough for SPOJ.