patience-0.1.1: Patience diff and longest increasing subsequence

Data.Algorithm.Patience

Description

Implements "patience diff" and the patience algorithm for the longest increasing subsequence problem.

Synopsis

# Patience diff

diff :: Ord t => [t] -> [t] -> [Item t]Source

The difference between two lists, according to the "patience diff" algorithm.

data Item t Source

An element of a computed difference.

Constructors

 Old t Value taken from the "old" list, i.e. left argument to `diff` New t Value taken from the "new" list, i.e. right argument to `diff` Both t t Value taken from both lists. Both values are provided, in case your type has a non-structural definition of equality.

Instances

 Functor Item Typeable1 Item Eq t => Eq (Item t) Data t => Data (Item t) Ord t => Ord (Item t) Read t => Read (Item t) Show t => Show (Item t)

itemChar :: Item t -> CharSource

The character `'-'` or `'+'` or `' '` for `Old` or `New` or `Both` respectively.

itemValue :: Item t -> tSource

The value from an `Item`. For `Both`, returns the "old" value.

# Longest increasing subsequence

longestIncreasing :: [(Int, a)] -> [(Int, a)]Source

Given: a list of distinct integers. Picks a subset of the integers in the same order, i.e. a subsequence, with the property that

• it is monotonically increasing, and
• it is at least as long as any other such subsequence.

This function uses patience sort: http://en.wikipedia.org/wiki/Patience_sorting. For implementation reasons, the actual list returned is the reverse of the subsequence.

You can pair each integer with an arbitrary annotation, which will be carried through the algorithm.