Difference between revisions of "Euler problems/161 to 170"

== [http://projecteuler.net/index.php?section=problems&id=161 Problem 161] ==

Triominoes

Solution:

<haskell>

problem_161 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=162 Problem 162] ==

Hexadecimal numbers

Solution:

<haskell>

problem_162 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=163 Problem 163] ==

Cross-hatched triangles

Solution:

<haskell>

problem_163 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=164 Problem 164] ==

Numbers for which no three consecutive digits have a sum greater than a given value.

Solution:

<haskell>

addDigit x = [[sum [x !! b !! c | c <- [0..9-a-b]] | b <- [0..9-a]] | a<-[0..9]]

x3 = [[10-a-b | b <- [0..9-a]] | a <- [0..9]]

x20 = iterate addDigit x3 !! 17

problem_164 = sum [x20 !! a !! b | a <- [1..9], b <- [0..9-a]]

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=165 Problem 165] ==

Intersections

Solution:

<haskell>

problem_165 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=166 Problem 166] ==

Criss Cross

Solution:

<haskell>

problem_166 =

sum [ product (map count [[0, c, b-d, a-b-d],

[0, b-a, c+d-a, b+d-a],

[0, -b-c, a-b-c-d, -c-d],

[0, a, d, c+d]])|

a <- [-9..9],

b <- [-9+a..9+a],

c <- [-9..9],

d <- [-9+a-c..9+a-c]]

where

count xs

|u<l=0

|otherwise=u-l+1

where

l = -minimum xs

u = 9-maximum xs

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=167 Problem 167] ==

Investigating Ulam sequences

Solution:

<haskell>

problem_167 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=168 Problem 168] ==

Number Rotations

Solution:

<haskell>

problem_168 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=169 Problem 169] ==

Exploring the number of different ways a number can be expressed as a sum of powers of 2.

Solution:

<haskell>

problem_169 = undefined

</haskell>

== [http://projecteuler.net/index.php?section=problems&id=170 Problem 170] ==

Find the largest 0 to 9 pandigital that can be formed by concatenating products.

Solution:

<haskell>

problem_170 = undefined

</haskell>