# Euler problems/181 to 190

### From HaskellWiki

## 1 Problem 181

Investigating in how many ways objects of two different colours can be grouped.

Solution: This was my code, published here without my permission nor any attribution, shame on whoever put it here. Daniel.is.fischer

## 2 Problem 182

RSA encryption.

Solution:

fun a1 b1 = sum [ e | e <- [2..a*b-1], gcd e (a*b) == 1, gcd (e-1) a == 2, gcd (e-1) b == 2 ] where a=a1-1 b=b1-1 problem_182=fun 1009 3643

## 3 Problem 183

Maximum product of parts.

Solution:

pmax x a=a*(log x-log a) tofloat x=encodeFloat x 0 fun x= div n1 $gcd n1 x where e=exp 1 n=floor(fromInteger x/e) n1=snd.maximum$[(b,a)|a<-[n..n+1],let b=pmax (tofloat x) (tofloat a)] n `splitWith` p = doSplitWith 0 n where doSplitWith s t | p `divides` t = doSplitWith (s+1) (t `div` p) | otherwise = (s, t) d `divides` n = n `mod` d == 0 funD x |is25 k=(-x) |otherwise =x where k=fun x is25 x |s==1=True |otherwise=False where s=snd(splitWith (snd (splitWith x 2)) 5) problem_183 =sum[funD a|a<- [5..10000]]