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lim=int(1000000007) t = int(input()) for i in range(t): n,c =input().split() n=int(n) c=int(c) if n%2==1: g1 =c**(5*n*n)%lim g2=(c**(n*n+(n*n+1)/2)) %lim g2 =2*g2 g3 =c**(2*n*n+(n*n+1)/2) %lim print (int(((g1+g2+g3)/4))%lim) else : g1 =c**(5*n*n)%lim g2=(c**(n*n+(n*n)/4)) %lim g2 =2*g2%lim g3 =c**(2*n*n+(n*n)/2) %lim print (int(((g1+g2+g3)/4))%lim) Link to the problem

I have solved this problem but I am not able to pass the timelimit Can someone tell the improvement in the code ..

asked 21 Jul '17, 16:34

mabrinmacro's gravatar image

accept rate: 0%

edited 21 Jul '17, 16:36

Just try to run with the following input:

1 1
1 2
100 3

You will get an overflow. In your code, you are calculating c to power O(n^2). Which is super exponential w.r.t. n. Just n=100 and c=2 leads to an overflow. Just think what will happen with the largest possible inputs. For example,

c = 10^9
n = 10^18

which will lead to c^10^36. That's a HUGEEEE number. Obviously your code will break. Try to come up with another algorithm and think about when you should be using the MOD limit of 10^9+7.

There is a catch while writing Python codes. As the popular saying goes: With great power comes great responsibilities. Similarly, with great Python one liners, comes a great responsibility of understanding what's going on behind the scene and what complexity a library call involves.


answered 21 Jul '17, 17:04

utkalsinha's gravatar image

accept rate: 13%

edited 21 Jul '17, 17:09

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question asked: 21 Jul '17, 16:34

question was seen: 245 times

last updated: 21 Jul '17, 17:09