SST 2022 S4 Computing Prelim P2 Ans

1 2022 SEC 4 COMPUTING PRELIM PAPER 2 MARKING SCHEME Task 1 Question Answer 1 =MEDIAN(B3:B12) Question Answer 2 =SUMIF(C3:C12,">=10",B3:B12) Question Answer 3 =B3*C3 Question Answer 4 =SUM(D3:D12) Question Answer 5 =MATH.FLOOR(D3) Question Answer 6 =IF(COUNTIF(B$19:F$19,A3)=1,HLOOKUP(A3,B$19:F$20,2,FALSE),"1") Question Answer 7

2 Task 2 Question Answer 8 Input of list_length from user, including input message. list_length = int(input("Please input the length of the list: ") for i in range(list_length): Question Answer 9 Flip the inequality sign in the function. if arr[p] < arr[p+1]: Question Answer 10 Looping the input. Checking if input is numeric using .isdigit() or equivalent. Checking for possibility of negative sign in the first index Shifting the typecasting to int from the input line to the line where valid input is added to the list Error message if input is not valid while True: num = input("Please input an integer: ") if num.isdigit() or (num[0] == "-" and num[1:].isdigit()): arr = arr + [int(num)] break else: print("Invalid input!") Question Answer 11 Looping through the list Comparing the numbers in the list Removing duplicate numbers OR Adding non-duplicate numbers to a second list -1m if all this is not done in UDF #after the list has been sorted in the UDF arr2 = [arr[0]] i = 1 while i < len(arr): if arr[i] != arr[i-1]: arr2 = arr2 + [arr[i]] i += 1

3 Sample Code: list_length = int(input("Please input the length of the list: ")) def bubblesort(arr): for r in range(1, list_length): for p in range(0, list_length - r): if arr[p] < arr[p+1]: #flip the inequality sign arr[p], arr[p+1] = arr[p+1], arr[p] arr2 = [arr[0]] i = 1 while i < len(arr): if arr[i] != arr[i-1]: arr2 = arr2 + [arr[i]] i += 1 return arr2 arr = [] for i in range(list_length): while True: num = input("Please input an integer: ") if num.isdigit() or (num[0] == "-" and num[1:].isdigit()): arr = arr + [int(num)] break else: print("Invalid input!") print("The sorted list:", bubblesort(arr))

4 Task 3 Question Answer 12 print('Welcome to Buttercup Customised Bouquets!') print('Enter up to three flowers to create your bouquet.') flowers = ['red roses', 'pink roses', 'buttercups', "baby's breath", 'limonium'] #syntax: inverted commas prices = [7, 9, 10, 3, 5] counter = 0 cost = 5 #logic: including a base cost of 5 while counter < 3: #logic: while instead of if flower = input('Please choose a flower: ') flower = flower.lower() #logic: lower instead of islower if flower not in flowers: print('Sorry, we do not have that flower. Please try again!') continue #syntax: missing indent flower_index = flowers.index(flower) cost += prices[flower_index] #logic: flower_index instead of flower_index+1 counter += 1 if counter < 3: #logic: 3 instead of 2 cont = input('Please enter "N" to end, or any other key to continue: ').upper() if cont == 'N': break #syntax: double == sign; logic: 'N' instead of 'n' if counter == 3: cost = round(0.9 * cost, 2) #syntax: round function instead of int print('The cost of your bouquet is ${}.'.format(cost))

5 Task 4 Question Answer 13 Proper naming of method signature and variable Use math.ceil or round to derived cost Return appropriate variable Question Answer 14 Input statement for N, user_weight Input statement for X and S with .split() Input validation for X and S Calling get_cost() to calculate cost Display all N companies name and cost quotes All input and output must have appropriate prompts. Question Answer 15 Output matches stored program Results are accurate, as reflected below Question Answer 16 Using loop to find lowest (a) price quote based on user_weight Display company(s) with the cheapest price quote Calculate lowest (b) cost per kilogram of user_weight Display company(s) with the cheapest price quote per kilogram Question Answer 17 Test case 1: TW = 18, MW = 6 Test case 2: TW = 20, MW = 5 Test case 3: TW = 30, MW = 8

6 Sample Code: # Q13 import math def get_quotes(weight, price, est_weight): weight_req = math.ceil(est_weight/weight) return price * weight_req #non math module solution def get_quotes2(weight, price, est_weight): weight_req = int((est_weight/weight)+0.5) return price * weight_req #driver test print(get_quotes(20, 10, 30)) print(get_quotes2(20, 10, 30)) # Q14 # continue from Q13 N = int(input("Enter the number of companies: ")) validated = False while not validated: x = input("Enter {} number of weights (X): ".format(N)).split() if len(x) != N: print("Invalid number of weights (X) entered. Please re-enter.") else: validated = True for i in range(N): x[i] = float(x[i]) validated = False while not validated: s = input("Enter {} number of costs (S): ".format(N)).split() if len(s) != N: print("Invalid number of costs (S) entered. Please re-enter.") else: validated = True for i in range(N): s[i] = float(s[i]) print() user_weight = int(input("Enter the estimated weight to be moved: ")) costs = [] print("Weight to move: {}".format(user_weight)) print("Company\tQuotes") for i in range(N): temp = get_quotes(x[i], s[i], user_weight) costs.append(temp) print("{}\t{}".format(chr(65+i), costs[i]))

7 # Q15 # Q16 # continue from Q14 coy_per_userwt, coy_per_kilo = 'A', 'A' cost_per_userwt, cost_per_kilo = costs[0], (s[0]/x[0]) for i in range(N): if cost_per_userwt > costs[i]: cost_per_userwt = costs[i] coy_per_userwt = chr(65+i) temp = s[i] / x[i] if temp < cost_per_kilo: cost_per_kilo = temp coy_per_kilo = chr(65+i) print() print("Cheapest quote based on user weight: {} at ${}".format(coy_per_userwt,cost_per_userwt)) print("Cheapest quote based on per kilo: {} at ${}".format(coy_per_kilo,cost_per_kilo)) # Q17 def maxCombo(tw, mw): if (tw < mw): return 0 count = 1 for i in range(mw, int(tw/2)+1): count += maxCombo(tw-i, i) return count #Driver Test print("TW:{} MW:{} -> {}".format(18, 6, maxCombo(18, 6))) print("TW:{} MW:{} -> {}".format(20, 5, maxCombo(20, 5))) print("TW:{} MW:{} -> {}".format(30, 8, maxCombo(30, 8)))