Integer Overflow in a problem while using cout statement although i am using mod

Asked Apr 13 '20 at 18:20

Active Apr 13 '20 at 18:20

Viewed 45 times

cout<<((n%mod*n%mod)%mod)

when the value of n is:

2248813659738258

my output is :

-840739582

However this problem is resolved when using 'printf' instead of cout the reason for this problem??.

asked Apr 13 '20 at 18:20

Ryednap

1

There is no problem. Except `printf` being a C library function that's not type-safe, and shows the wrong results. It's the `printf` result that's incorrect. – Sam Varshavchik Apr 13 '20 at 18:22
4

Lot of things could be going wrong. Could we see a [mcve]? – user4581301 Apr 13 '20 at 18:23
1

What is the value of `mod`? Your calculation of `n % mod * n` is probably overflowing. – 1201ProgramAlarm Apr 13 '20 at 18:46
1

I guess value of mod is 1000000009 right?? – Chandra Shekhar Apr 13 '20 at 19:43
1

To prevent overflow, try: ((n%mod)*(n%mod)). Currently you effectively have ((((n%mod)*n)%mod)%mod) which is obviously not what you want, the second modulo is too late and the third modulo does nothing at all. – numzero Apr 14 '20 at 00:14
the value of 'mod' is 1000000007 – Ryednap Apr 14 '20 at 10:33

0 Answers0