Add CT331 Programming Paradigms

third/semester1/CT331: Programming Paradigms/assignments/assignment3/code/question1.prolog

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+takes(tom, ct331). 
+takes(mary, ct331). 
+takes(joe, ct331). 
+takes(tom, ct345). 
+takes(mary, ct345). 
+instructs(bob, ct331). 
+instructs(ann, ct345).  
+
+% 1. rule that returns true if a given instructor teaches a given student
+teaches(Instructor, Student) :- instructs(Instructor, Course), takes(Student, Course).
+
+% 2. query that uses the `teaches` rule to show all students instructed by bob
+?- teaches(bob, Student).
+?- findall(Student, teaches(bob, Student), Students).
+
+% 3. query that uses the `teaches` rule to show all instructors that instruct mary
+?- teaches(Instructor, mary).
+?- findall(Instructor, teaches(Instructor, mary), Instructors).
+
+% 5. rule that returns true if two students take the same course
+takesSameCourse(Student1, Student2) :- takes(Student1, Course), takes(Student2, Course).
+
+contains1(Element, [Element | Tail]).
+
+
+contains2(Sublist, [Head | Sublist]).

third/semester1/CT331: Programming Paradigms/assignments/assignment3/code/question3.prolog

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+% base case: any element is not in an empty list
+isNotElementInList(_, []).
+
+% return true if Element is not the Head of the list and it's not found recursively searching the rest of the list
+isNotElementInList(Element, [Head | Tail]) :- Element \= Head, isNotElementInList(Element, Tail).

third/semester1/CT331: Programming Paradigms/assignments/assignment3/code/question4.prolog

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+% predicate to merge two lists
+% base case: if the first list is empty, just return the second
+mergeTwoLists([], List, List).
+
+% recursive predicate to merge two lists
+% split the first list into head and tail, and recurse with its tail and the second list until the first list is empty (base case)
+% then merge the original head of the first list with the resulting tail
+mergeTwoLists([Head | Tail], List2, [Head | ResultTail]) :- mergeTwoLists(Tail, List2, ResultTail).
+
+% predicate to merge 3 lists 
+% base case: merging an empty list and two others is the same as merging two lists
+mergeLists([], List2, List3, Merged) :- mergeTwoLists(List2, List3, Merged).
+
+% split the first list into head and tail, and recurse with its tail and the other two lists until the first list is empty (base case)
+mergeLists([Head1 | Tail1], List2, List3, [Head1 | MergedTail]) :- mergeLists(Tail1, List2, List3, MergedTail).
+

third/semester1/CT331: Programming Paradigms/assignments/assignment3/code/question5.prolog

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+% call the helper predicate with the list to be reversed and an empty Accumulator to build up
+reverseList(List, Reversed) :- reverseListHelper(List, [], Reversed).
+
+% base case fact: when the list to reverse is empty, the accumulator is the reversed list
+reverseListHelper([], Accumulator, Accumulator).
+
+% recurse with the tail after prepending the head to the accumulator
+reverseListHelper([Head | Tail], Accumulator, Reversed) :- reverseListHelper(Tail, [Head | Accumulator], Reversed).

third/semester1/CT331: Programming Paradigms/assignments/assignment3/code/question6.prolog

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+% base fact: if the list is empty, the list to be returned is just the element
+insertInOrder(Element, [], [Element]).
+
+% if the element to be inserted is <= the head of the list, insert it at the head of the list
+insertInOrder(Element, [Head | Tail], [Element, Head | Tail]) :- Element =< Head.
+
+% if the element to be inserted is greater than the head of the list, recurse with the tail of the list until 
+insertInOrder(Element, [Head | Tail], [Head | NewTail]) :- Element > Head, insertInOrder(Element, Tail, NewTail).