10 Python Coding Shortcuts That Save Time in Exams

Every Second Counts in HKDSE

Paper 1 is 105 minutes. These shortcuts shave seconds off every question.

1. Swap Variables in One Line

# Long way (using temp)
temp = a
a = b
b = temp

# Short way
a, b = b, a

2. Multiple Assignment

# Assign same value
x = y = z = 0

# Assign different values
name, age, school = "Chan", 17, "Victoria"

3. Chained Comparisons

# Instead of:
if x > 0 and x < 10:

# Use:
if 0 < x < 10:

4. Ternary If

# Instead of 4 lines:
if score >= 50:
    status = "pass"
else:
    status = "fail"

# Use 1 line:
status = "pass" if score >= 50 else "fail"

5. String Multiplication

# Instead of a loop:
line = "-" * 30
# "------------------------------"

# Print headers instantly
print("=" * 20)
print("REPORT")
print("=" * 20)

6. List of Zeros

# Instead of a loop:
zeros = [0] * 10
# [0,0,0,0,0,0,0,0,0,0]

# 2D list of zeros
grid = [[0] * 3 for _ in range(3)]

7. enumerate for Index+Value

# Instead of:
i = 0
for item in lst:
    print(i, item)
    i += 1

# Use:
for i, item in enumerate(lst):
    print(i, item)

8. sum() With Condition

# Count pass scores
passes = sum(1 for s in scores if s >= 50)
# equivalent to: len([s for s in scores if s >= 50])

9. Min/Max with key

students = [("Chan", 85), ("Lee", 72)]
top = max(students, key=lambda x: x[1])
# ("Chan", 85)

10. Unpacking in Function Calls

lst = [1, 2, 3]
print(*lst)      # 1 2 3 (unpacked)
print(*"HKDSE", sep="-")   # H-K-D-S-E

Bonus: Input Multiple Numbers

# Instead of 3 lines:
a = int(input())
b = int(input())
c = int(input())

# Use:
a, b, c = map(int, input().split())