Write exercises

Remember, you can test your code out on TryAPL before submitting it here! You can submit as many solutions as you like.

Since this course is still a work-in-progress, solving the write exercises will currently not lead to any credits.

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Write problem 1

Create a vector consisting of the first ten prime numbers called PRIMES

PRIMES← Submit

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Write problem 2

Create a vector called POWER of value 2 to the power of PRIMES, minus two

POWER← Submit

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Write problem 3

Divide the vector POWER by PRIMES

⎕← Submit

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Write problem 4

Create the word "BUNNY" by indexing the alphabet vector ⎕A

⎕← ⎕A[ Submit

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Write problem 5

The following matrix CIPHER consists of shifted versions of the alphabet for every row.

      CIPHER ← (26 27 ⍴ ⎕A)[;1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26]
      CIPHER
  ABCDEFGHIJKLMNOPQRSTUVWXYZ
  BCDEFGHIJKLMNOPQRSTUVWXYZA
  CDEFGHIJKLMNOPQRSTUVWXYZAB
  DEFGHIJKLMNOPQRSTUVWXYZABC
  EFGHIJKLMNOPQRSTUVWXYZABCD
  FGHIJKLMNOPQRSTUVWXYZABCDE
  GHIJKLMNOPQRSTUVWXYZABCDEF
  HIJKLMNOPQRSTUVWXYZABCDEFG
  IJKLMNOPQRSTUVWXYZABCDEFGH
  JKLMNOPQRSTUVWXYZABCDEFGHI
  KLMNOPQRSTUVWXYZABCDEFGHIJ
  LMNOPQRSTUVWXYZABCDEFGHIJK
  MNOPQRSTUVWXYZABCDEFGHIJKL
  NOPQRSTUVWXYZABCDEFGHIJKLM
  OPQRSTUVWXYZABCDEFGHIJKLMN
  PQRSTUVWXYZABCDEFGHIJKLMNO
  QRSTUVWXYZABCDEFGHIJKLMNOP
  RSTUVWXYZABCDEFGHIJKLMNOPQ
  STUVWXYZABCDEFGHIJKLMNOPQR
  TUVWXYZABCDEFGHIJKLMNOPQRS
  UVWXYZABCDEFGHIJKLMNOPQRST
  VWXYZABCDEFGHIJKLMNOPQRSTU
  WXYZABCDEFGHIJKLMNOPQRSTUV
  XYZABCDEFGHIJKLMNOPQRSTUVW
  YZABCDEFGHIJKLMNOPQRSTUVWX
  ZABCDEFGHIJKLMNOPQRSTUVWXY

The Caesar cipher encrypts a phrase by shifting all its letters by a specific amount along the alphabet. For example, "ARENA" becomes "RIVER" under a shift of 17 places. Use indexing of the above matrix to encipher the word "BUNNY" by shifting its letters 17 places.

⎕← CIPHER[ Submit

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Write problem 6

Consider the following ASCII art stored in a matrix called ART, shown here with its row and column numbers.

   123456789111111111122222222
            012345678901234567
 1      ._________________.
 2      |.---------------.|
 3      ||  __  ____ __  ||
 4      || / _\(  _ (  ) ||
 5      ||/    \) __/ (_/||
 6      ||\_/\_(__) \____||
 7      ||_______________||
 8      /.-.-.-.-.-.-.-.-.\
 9     /.-.-.-.-.-.-.-.-.-.\
10    /.-.-.-.-.-.-.-.-.-.-.\
11   /______/__________\_____\
12   \_______________________/

Create a matrix called APL which consists of the following subarray obtained by indexing ART

  __  ____ __  
 / _\(  _ (  ) 
/    \) __/ (_/
\_/\_(__) \____

APL← ART[ Submit

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Write problem 7

Create a 3 by 3 grid of 'X's and 'O's called BOARD

BOARD← 'XO' Submit

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Write problem 8

Considering the above array as a game of noughts and crosses, change a single element to make the O player win.

⎕← BOARD[ Submit

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Write problem 9

Given the coefficients list C of a quadratic \(P(x) = C[1] x^2 + C[2] x + C[3]\), evaluate the polynomial for a value X. For example, for C ← 1 2 3, and X ← 10, this should evaluate to $ 1 \cdot 10^2 + 2 \cdot 10 + 3 = 123 $.

⎕← Submit

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Write problem 10

Consider the following list of GAMES

      GAMES ← 5 24 ⍴ 'CHESS                   CHECKERS                BACKGAMMON              POKER                   GLOBAL THERMONUCLEAR WAR'
      GAMES
CHESS                   
CHECKERS                
BACKGAMMON              
POKER                   
GLOBAL THERMONUCLEAR WAR

Get the first letter of each of the games listed using indexing

⎕← GAMES[ Submit

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Write problem 11

Get the first three letters of the second and fifth game listed above using indexing

⎕← GAMES[ Submit

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Write problem 12

Consider the following matrix ROUND of the outcomes of a game of rock, paper, scissors.

      ROUND ← 3 3 ⍴ 'DRAW' 'P2 COVERS' 'P1 BLUNTS' 'P1 COVERS' 'DRAW' 'P2 CUTS' 'P2 BLUNTS' 'P1 CUTS' 'DRAW'
      ROUND
┌─────────┬─────────┬─────────┐
│DRAW     │P2 COVERS│P1 BLUNTS│
├─────────┼─────────┼─────────┤
│P1 COVERS│DRAW     │P2 CUTS  │
├─────────┼─────────┼─────────┤
│P2 BLUNTS│P1 CUTS  │DRAW     │
└─────────┴─────────┴─────────┘

The rows specify the move made by player 1, and the columns the move made by player 2, both in the order ROCK, PAPER, SCISSORS.

Using indexing, find the outcome of the round in which player 1 plays scissors and player 2 plays paper.

⎕← ROUND[ Submit

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