Initial commit

Author: ChuntaoLu

Diff for: .gitignore

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+*~
+#*
+.idea/
+.swap

Diff for: README.md

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+##Paradigms of Computer Programming
+------
+Quizzes and homeworks for edX course **Paradigms of Computer Programming** 
+

Diff for: invariant_programming_and_lists/append.oz

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+declare
+fun {AppendLists L1 L2}
+   case L1 of
+      nil then L2
+   [] H|T then H|{AppendLists T L2}
+   end
+end
+
+{Browse {AppendLists [4] [1 2 3]}}
+{Browse {AppendLists [5 [6]] [1 2 3]}}

Diff for: invariant_programming_and_lists/factorial.py

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+"""
+The script below shows that Python does not support tail call optimization.
+"""
+from memory_profiler import profile
+
+
+def fact(n):
+    if n == 0:
+        return 1
+    else:
+        return n * fact(n - 1)
+
+
+def fact_tail(n, a=1):
+    if n == 0:
+        return a
+    else:
+        return fact_tail(n - 1, n * a)
+
+
+def fact_loop(n, a=1):
+    while True:
+        if n == 0:
+            return a
+        n, a = n - 1, n * a
+
+
+@profile
+def main(n):
+    #a = [fact_tail(i) for i in xrange(n)]
+    b = [fact(i) for i in xrange(n)]
+    #c = [fact_loop(i) for i in xrange(n)]
+
+if __name__ == '__main__':
+    main(500)

Diff for: invariant_programming_and_lists/find_in_list.oz

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+declare
+fun {Prefix L1 L2}
+   case L1 of
+      nil then true
+   [] H|T then
+      if L2 == nil then false
+      else H==L2.1 andthen {Prefix T L2.2} end
+   end
+end
+
+declare
+fun {FindString L1 L2}
+   if L2 == nil then {Prefix L1 L2}
+   else
+      if {Prefix L1 L2} then true
+      else {FindString L1 L2.2} end
+   end
+end
+
+{Browse {Prefix [1 2] [1 2 3]}}
+{Browse {Prefix nil [1 2 3]}}
+{Browse {Prefix [1] nil}}
+{Browse {FindString [1 3] [1 2 3]}}
+{Browse {FindString nil nil}}

Diff for: invariant_programming_and_lists/flatten_list.oz

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+declare
+fun {FlattenList L}
+   case L of
+      nil then L
+   [] H|T then
+      case H of
+         HH|HT then {Append {FlattenList H} {FlattenList T}}
+      else H|{FlattenList T}
+      end
+   end
+end
+
+{Browse {FlattenList [[1 2] [1 [2]]]}}
+{Browse {FlattenList [[1 2 [3 [4[5]]]] [1 [2]]]}}

Diff for: invariant_programming_and_lists/list_factorial.oz

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+declare
+fun {ListFact L}
+   fun {Fact N Acc}
+      if N<2 then Acc
+      else {Fact N-1 N*Acc} end
+   end
+in
+   case L of
+      nil then nil
+   [] H|T then {Fact H 1}|{ListFact T}
+   end
+end
+
+{Browse {ListFact [1 2 3]}}
+{Browse {ListFact [7 6 15]}}

Diff for: invariant_programming_and_lists/mirror.oz

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+declare
+fun {MainMirror N}
+   fun {Mirror N Acc}
+      if N==0 then Acc
+      else {Mirror (N div 10) Acc*10+(N mod 10)} end
+   end
+in
+   {Mirror N 0}
+end
+
+{Browse {MainMirror 1234}}
+{Browse {MainMirror 876465}}

Diff for: invariant_programming_and_lists/naive_fib.oz

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+declare
+fun {NaiveFib N}
+   case N of
+      0 then 0
+   [] 1 then 1
+   else {NaiveFib N-1} + {NaiveFib N-2}
+   end
+end
+
+{Browse {NaiveFib 32}}

Diff for: invariant_programming_and_lists/prime.oz

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+declare
+fun {Prime N}
+   fun {IsPrime N Acc}
+      if Acc==1 then true
+      else
+         if N mod Acc == 0 then false
+         else {IsPrime N Acc-1} end
+      end
+   end
+in
+   if N==1 then false
+   else {IsPrime N N-1} end
+end
+
+
+{Browse {Prime 1}}   
+{Browse {Prime 2}}   
+{Browse {Prime 13}}   
+{Browse {Prime 50}}   

Diff for: invariant_programming_and_lists/sum.oz

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+declare
+fun {MainSum N}
+   fun {Sum N Acc}
+      if N==0 then Acc
+      else {Sum N-1 N+Acc} end
+   end
+in
+   {Sum N 0}
+end
+
+{Browse {MainSum 10}}
+{Browse {MainSum 5}}

Diff for: invariant_programming_and_lists/tail_fib.oz

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+declare
+fun {TailFib N}
+   fun {Fib N Acc1 Acc2}
+      case N of
+         0 then Acc1
+      [] 1 then Acc2
+      else {Fib N-1 Acc2 Acc1+Acc2}
+      end
+   end
+in
+   {Fib N 0 1}
+end
+
+{Browse {TailFib 32}}
+{Browse {TailFib 42}}