Completing a partly written algorithm
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. A totalling loop adds 10 marks. What goes in the missing line? ___
FOR Index ← 1 TO 10
Total ← Total + Mark[Index]
NEXT Index
2. Finding the maximum in Mark[1:5]. Which start value is best for Max before the loop?
3. Name[1:30] holds 30 names and every one must be checked. Which loop line is missing the right bound?
4. Count the marks that are MORE than 50. Which condition completes the line? IF Mark[Index] ___ 50 THEN
5. A FOR loop contains an IF ... THEN statement. The IF is complete, but the line IF Score > Max THEN has no closing line. Which keyword is missing?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1Total ← ___ FOR i ← 0 TO 4 Total ← Total + Marks[i] NEXT i | AThe blank must be the last index of the array, such as 4 for an array of 5 items | |
| 2FOR i ← 0 TO ___ OUTPUT Marks[i] NEXT i | BMax starts at 0, which fails if all values are negative. Max should start as the first array element, Marks[0]. | |
| 3A counting algorithm needs a closing keyword for its IF statement inside the loop, so the missing line is ENDIF | CFOR i ← 0 TO 9 IF Score[i] > 50 THEN Count ← Count + 1 ENDIF NEXT i | |
| 4A linear search with a WHILE loop must keep going only while the item is not found and the end of the list is not reached | DThe blank must be 0, so the total starts empty before any marks are added | |
| 5Max ← 0 FOR i ← 0 TO 4 IF Marks[i] > Max THEN Max ← Marks[i] ENDIF NEXT i | EWHILE Found = FALSE AND i <= 9 DO IF Names[i] = Target THEN Found ← TRUE ENDIF i ← i + 1 ENDWHILE | |
| 6REPEAT INPUT Num Total ← Total + Num ENDWHILE | FThe wrong closing keyword is used. A REPEAT loop must end with UNTIL and a condition, not ENDWHILE. |
C
Definitions
complete the algorithm
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
Total ← _
FOR Index ← 1 TO 5
Total ← Total + Num[Index]
2.
DECLARE Mark : ARRAY[1:10] OF INTEGER
FOR Index ← 1 TO __
Total ← Total + Mark[Index]
3.
IF Mark[Index] _ Max THEN
Max ← Mark[Index]
ENDIF
4.
FOR Index ← 1 TO 10
Total ← Total + Mark[Index]
____ Index
5.
REPEAT
INPUT Guess
_____ Guess = 42
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
Max ← Score[1]
B
FOR i ← 2 TO 8
C
IF Score[i] < Max THEN
D
Max ← Score[i]
E
ENDIF
F
NEXT i
Question 2
A
Count ← 1
B
FOR i ← 1 TO 10
C
IF Mark[i] > 50 THEN
D
Count ← Count + 1
E
ENDIF
F
NEXT i
Question 3
A
Sum ← 0
B
FOR i ← 1 TO 4
C
INPUT Mark
D
Sum ← Sum + Mark
E
NEXT i
F
OUTPUT Sum / 5
Question 4
A
Total ← 0
B
FOR i ← 1 TO 10
C
Total ← Total + Mark[i]
D
ENDFOR
E
OUTPUT Total
Question 5
A
Min ← 0
B
FOR i ← 2 TO 7
C
IF Temp[i] < Min THEN
D
Min ← Temp[i]
E
ENDIF
F
NEXT i
Answer Key
Completing a partly written algorithm
Section A: Quick Questions
Q1
B — Total ← 0
Q2
A — Max ← Mark[1]
Q3
B — FOR Index ← 1 TO 30
Q4
A — >
Q5
A — ENDIF
Section B: Match the Pairs
Q1
Total ← ___
FOR i ← 0 TO 4
Total ← Total + Marks[i]
NEXT i → The blank must be 0, so the total starts empty before any marks are added
Q2
FOR i ← 0 TO ___
OUTPUT Marks[i]
NEXT i → The blank must be the last index of the array, such as 4 for an array of 5 items
Q3
A counting algorithm needs a closing keyword for its IF statement inside the loop, so the missing line is ENDIF → FOR i ← 0 TO 9
IF Score[i] > 50 THEN
Count ← Count + 1
ENDIF
NEXT i
Q4
A linear search with a WHILE loop must keep going only while the item is not found and the end of the list is not reached → WHILE Found = FALSE AND i <= 9 DO
IF Names[i] = Target THEN
Found ← TRUE
ENDIF
i ← i + 1
ENDWHILE
Q5
Max ← 0
FOR i ← 0 TO 4
IF Marks[i] > Max THEN
Max ← Marks[i]
ENDIF
NEXT i → Max starts at 0, which fails if all values are negative. Max should start as the first array element, Marks[0].
Q6
REPEAT
INPUT Num
Total ← Total + Num
ENDWHILE → The wrong closing keyword is used. A REPEAT loop must end with UNTIL and a condition, not ENDWHILE.
Section C: Definitions
Q1
complete the algorithm — Fill each missing line or value by asking what the standard method (total, count, max, search, sort) needs at that point: start value, loop bound, condition or closing keyword.Section D: Fill in the Blanks
Q1
Total ← 0
FOR Index ← 1 TO 5
Total ← Total + Num[Index]Q2
DECLARE Mark : ARRAY[1:10] OF INTEGER
FOR Index ← 1 TO 10
Total ← Total + Mark[Index]Q3
IF Mark[Index] > Max THEN
Max ← Mark[Index]
ENDIFQ4
FOR Index ← 1 TO 10
Total ← Total + Mark[Index]
NEXT IndexQ5
REPEAT
INPUT Guess
UNTIL Guess = 42Section E: Spot the Error
Q1
C — To find the maximum, the condition must check for a score greater than Max. Using < would find the minimum instead. It should be IF Score[i] > Max THEN.
Q2
A — A counter must start at 0 so that it counts only the items that meet the condition. Starting at 1 makes the final count one too high. It should be Count ← 0.
Q3
B — There are 5 marks, so the loop bound must be 5. With TO 4 the last mark is never added, but the total is still divided by 5. It should be FOR i ← 1 TO 5.
Q4
D — In Cambridge pseudocode a FOR loop is closed with NEXT, not ENDFOR. The line should be NEXT i.
Q5
A — The minimum must start as the first item in the array. Starting at 0 means no temperature above 0 can ever be smaller, so the result would be wrong. It should be Min ← Temp[1].