exercises-4clojure.clj

;;; Put your solutions to the assigned 4Clojure exercises here and commit
;;; back up to your fork on Github.

;;; What you enter is whatever you'd put in the "Code which fills in the blank"
;;; box in 4Clojure. You're welcome to include other things here (helper definitions,
;;; scratch computations you found helpful, etc.), SO MAKE SURE YOU LABEL YOUR
;;; "ANSWERS" clearly.

;;; I've included a few examples below just to give you a sense of what I'm looking
;;; for.

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;;; Problem #162: Logical falsity and true

; What I pasted in the box:
1

; because all the given expressions returned 1, for example:
(= 1 (if [] 1 0))

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;;; Problem #15: Double Down

; What I pasted in the box:
#(* 2 %)

; which is an anonymous function that doubles its argument, for example:
(= (#(* 2 %) 11) 22)

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;;;;; TO DO

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;;; Problem 10 - Intro To Maps

; What I put:
20

; considered it like stored values
; value at :b is 20 for both

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;;; Problem 16 - Hello World

; What I put:
(fn [name] (format "Hello, %s!" name))

; %s designates where to put name in the string

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;;; Problem 17 - Sequences: map

; What I put:
'(6 7 8)

; nameless function takes each number from the list and adds 5 to it

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;;; Problem 18 - Sequences: filter

; What I put:
'(6 7)

; filter checks numbers from list 
; if number is > 5 then its in the new list (stays in the list)

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;;; Problem 20 - Penultimate Element

; What I put:
#(.get %(- (count %) 2))

; count = length of list
; - 2 to get second to last item

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;;; Problem 21 - Nth Element

; What I put:
#(last (take (+ %2 1) %1))

; take gets all the elements up to what given (n) + 1
; last gets the last element of the new set of elements

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;;; Problem 23 - Reverse a sequence

; What I put:
#(into () %)

; into puts elements at the head of the set individually (reversing it)

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;;; Problem 25 - Find the odd numbers

; What I put:
#(filter odd? %)

; Filter goes through whole lists
; if number is odd, it's included

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;;; Problem 37 - Regular Expressions

; What I put:
"ABC"

; Reading the sequence looking for only capital letters

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;;; Problem 40 - Interpose a sequence

; What I put:
#(drop-last (interleave %2 (repeat %1)))

; repeat gives me the inputs, interleave puts things in
; just have to drop the last input and whala!

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;;; Problem 43 - Reverse interleave

;
#((let [x (count %1)
        y (/ x %1) ]
   (partition y %2) ))

; Get ClassCastException, but I know I'm really close.

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;;; Problem 44 - Rotate sequence

; What I put:
#(let 
   [x (count %2)
    a (if (neg? %1) 
        (take (inc (+ x %1)) %2)
        (take %1 %2)
       )
    b (if (neg? %1) 
        (reverse (take (* -1 %1) (reverse %2)))
        (reverse (take (- x %1) (reverse %2)))
       )
    ]
   (concat b a)
  )

; Only passes first one.
; Hypothesis: 
;   My positive rotations work while my negatives don't.

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;;; Problem 46 - Flipping out

; What I put:
#(fn ([x y] (% y x)))

; Literally filipping x & y (the two argument) when calling function (%)

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;;; Problem 47 - Contain yourself

; What I put:
4

; for #{4 5 6}, there is a 4
; [1 1 1 1 1], there is atleast 4 indices
; [2 3 4], only has 3 indices so false and (not [2 3 4]) is true

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