Fall 2017 Midterm Exam 1 October 19, You may not use any books, notes, or electronic devices during this exam.

Transcription

1 Fll 2017 Midterm Exm 1 October 19, 2017 Nme: Andrew ID: Recittion Section: You my not use ny books, notes, or electronic devices during this exm. You my not sk questions bout the exm except for lnguge clrifictions. Show your work on the exm to receive credit. You my use the bcks of pges s scrtch pper. Nothing written on the bck of ny pges will be grded. All code smples run without crshing. Assume ny imports re lredy included s required. Do not use these post-midterm 1 topics/constructs: sets, mps/dictionries, recursion, or clsses/oop. Don t write nything in the tble below. Question Points Score Totl: 100

2 1. Code Trcing Indicte wht ech will print. Plce your nswer (nd nothing else) in the box below ech block of code. () (5 points) CT1 import string def ct1(s): = "" for i in rnge(len(s)): if s[i] in string.digits: j = int(s[i]) print(s[i::j]) elif s[i] in string.scii_lowercse: s = s.upper() += s[i] elif s[i] in string.scii_uppercse: s = s.lower() += s[i] print() ct1("2hg5e\td3b1") Pge 1 of 14

3 (b) (5 points) CT2 import copy def ct2(): b = c = copy.copy() d = copy.deepcopy() c[0] = [4, 6] b[0][1] = "ornge" c[1][0] = "lime" c[0][0] = 10 d[1] = [7, 9] c[1].insert(1,3) b.ppend("ct") print(" =", ) print("b =", b) print("c =", c) print("d =", d) z = [ [2, 3], [11, 12] ] ct2(z) print("z =", z) Pge 2 of 14

4 2. Resoning Over Code For ech function, find vlues of the prmeters so tht the function will return True. Plce your nswer (nd nothing else) in the box below ech block of code. () (5 points) ROC1 def roc1(n): ssert(n < ) (, b) = (0, 0) while n > 0: (c, n) = (n % 10, n // 10) if c < 5: = 10* + c else: b = 10*b + c return (, b) == (30, 795) (b) (5 points) ROC2 def roc2(l): if not isinstnce(l, list): return Flse = len(l) s = L.pop() for i in rnge(2): s += L.pop(s) for i in L: s -= (ord(i) - ord( )) return s == 33 nd > 3 nd < 10 Pge 3 of 14

5 3. Short Answer Answer ech of the following very briefly. () (3 points) Consider the following code tht we went over in lecture: def hsblncedprentheses(s): leftpren = 0 rightpren = 0 for c in s: if c == "(": leftpren += 1 elif c == ")": rightpren += 1 return leftpren == rightpren Describe why this is not good solution to the problem. (b) (3 points) Consider the following screenshot of tkinter gme: The grid you see consists of squres with 80 pixel sides nd mrgin of 40 pixels ll round. The gme ends when the user clicks on the colored cell. The vribles dt.row nd dt.col define the row nd column, respectively, of which cell is colored. In the exmple picture, the row is 2 nd the column is 1. When the user clicks on the colored cell, dt.gmeover should be set to true. Fill in 3-4 lines of python code to complete the mousepressed function s described bove. def mousepressed(event, dt): Pge 4 of 14

6 (c) (3 points) Wht is the primry difference between tuple nd list? (d) (3 points) Write comment of fifteen words or less tht describes wht the following function does. def puzzle(): ssert(isinstnce(, list)) c = len() d = 0 for i in rnge(c): e = c - i - 1 if i >= e: brek elif [i] == [e]: d += 1 return d == c // 2 (e) (3 points) Define nd briefly explin wht the three elements of MVC re. Pge 5 of 14

7 4. (20 points) Free Response: Prdish Numbers Note: For full credit, you my not use strings or lists for this problem. deduction, you my use strings nd/or lists. A prdish number (coined term) is number with ll of the following properties: The number hs n even number of digits. For 10-pt The sum of the digits of the number is equl to the number of digits of the number. The sum of the first hlf of the digits is equl to the sum of the second hlf of the digits. For exmple, is prdish. It hs 6 digits, which is even. Its digits lso sum to 6 ( = 6). The sum of the first hlf of the digits is equl to the sum of the second hlf of the digits ( = ). Write the function isprdish(n) tht tkes n integer vlue n nd returns True if the number is prdish nd flse otherwise. Then, write nthprdish(n) tht tkes n integer vlue n nd returns the nth prdish number. For exmple, nthprdish(0) returns 11. You my write ny dditionl helper functions you desire. Pge 6 of 14

8 Additionl Spce for Answer to Question 4 Pge 7 of 14

9 5. (20 points) Free Response: Verticl Word Remover In this problem you will write the destructive function verticlwordremove(l, word) tht tkes s rguments non-rgged, 2-dimensionl list L of letters nd string word. The function goes through L, removing the first instnce of the word from the columns of L, shifting the rows to the left to fill in the empty spces s it goes. Consider the following exmple: L = [ [ t, c, z, d, e, f, g ], [,, d, f, d, c, ], [ c, t, q, r, e,, q ], [ w, e, i, o, t, t, w ] ] After clling verticlwordremove(l, "ct"), then... L = [ [ t, z, d, e, f, g ], [, d, f, d, c, ], [ c, q, r, e,, q ], [ w, e, i, o, t, t, w ] ] The word ct ws removed from column 1. Notice tht even though L hs two instnces of ct in its columns, only the first one is removed. Notes: When your function is clled, you my ssume L is not rgged. After your function returns, L might be rgged. You my ssume L nd word will contin only lowercse letters. You should serch the columns in left-right order (column 0, then 1, then 2, etc) nd within column serch top-down. Pge 8 of 14

10 Additionl Spce 1 for Answer to Question 5 Pge 9 of 14

11 Additionl Spce 2 for Answer to Question 5 Pge 10 of 14

12 6. (25 points) Free Response: Color Grid Animtion Assuming the run() function is lredy written for you, write init, keypressed, mouse- Pressed, redrwall, nd timerfired so tht when the nimtion is first run: A. A blck grid composed of red cells (ech 20 pixels by 20 pixels) is displyed in the window, with no mrgin. You my ssume the window s width nd height re ech multiples of 20. B. A blue circle is in the upper-left cell. Gme ply proceeds s such: A. Every hlf second, the circle moves forwrd one cell. At the beginning, the circle moves downwrds. B. The circle s color chnges utomticlly every five seconds. The color switches from blue to red nd from red to blue. C. When the circle moves into new cell, it chnges tht cell s color to mtch its own. The cell keeps tht color when the circle leves. D. If the circle moves off the bord, the gme is over. This is displyed s blck screen with yellow text in the center which sys GAME OVER!. E. The user cn chnge the circle s movement direction by pressing the rrow keys. Mke resonble ssumptions for nything not specified here. Do not hrdcode vlues for dt.width or dt.height. You re only llowed to use one timer nd one timerfired function. We recommend tht, to sve time writing, you bbrevite cnvs, event, nd dt: use c, e nd d, respectively. Pge 11 of 14

13 Additionl Spce 1 for Answer to Question 6 Pge 12 of 14

14 Additionl Spce 2 for Answer to Question 6 Pge 13 of 14

15 Additionl Spce 3 for Answer to Question 6 Pge 14 of 14