Q1B

Author: roopansh

PrologProgramming/1B.pl

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+% returns the longest increasing subsequence
+lis(Input, Output) :-
+	% Aggregate all the increasing subsequences(In reverse order)
+	% Compare the lengths and store the max length subsequence in Result
+	aggregate(max(Len,IncSub),
+		  (one_is(Input, [], IncSub), length(IncSub, Len)),
+		  max(_, Result)),
+	% Reverse and output the result
+	reverse(Result, Output)
+	.
+
+
+% find increasing subsequence
+% If input becomes empty, then return the string in the
+% current(accumulator)
+one_is([], Current, Current).
+
+one_is([H | T], Current, Final) :-
+	% If the current(accumulator) is empty, push the head in accumulator
+	% and recurse
+	(   Current = [], one_is(T, [H], Final));
+	% If current is not empty, then push the head of input if
+	% it is larger than the head of the accumulator and recurse
+	(   Current = [H1 | _], H1 < H,   one_is(T, [H | Current], Final));
+	one_is(T, Current, Final).