23 lines
883 B
Smalltalk
23 lines
883 B
Smalltalk
Collection extend [
|
|
checkSafeStep: a to: b
|
|
[ (a < 1) | (b > self size) ifTrue: [^true].
|
|
^(self at: b) - (self at: a) between: 1 and: 3 ]
|
|
|
|
safetyFwd
|
|
[ | dp | dp := Array new: self size + 1.
|
|
(self size to: 0 by: -1) do: [
|
|
:i | i chain + 1;
|
|
to: i + 2; "or `self size + 1`, but only jumps of 1 are possible"
|
|
select: [ :j | self checkSafeStep: i to: j ];
|
|
collect: [ :j | (dp at: (j + 1) ifAbsent: [0]) + (j - i - 1) ];
|
|
minimum; >* [ :v | dp at: (i + 1) put: v ] ].
|
|
^dp at: 1 ]
|
|
safety [ ^self safetyFwd min: self reverse safetyFwd ]
|
|
]
|
|
|
|
AOC input: [ stdin toLines collect: [
|
|
:ln | ln chain tokenize: ' ';
|
|
collect: [ :lvl | lvl asNumber ]; safety ] ];
|
|
part1: 0; part2: 1;
|
|
result: [ :reports :damp | reports count: [ :it | it <= damp ] ];
|
|
finish
|