Continue statement behavior in Python - Time & Space Complexity

Time Complexity: Continue statement behavior

O(n)

Understanding Time Complexity

Let's explore how the continue statement affects the time complexity of loops.

We want to know how skipping some steps changes the total work done as input grows.

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

for i in range(n):
    if i % 2 == 0:
        continue
    print(i)

This code loops from 0 to n-1, but skips printing when the number is even.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The loop runs through all numbers from 0 to n-1.
• How many times: Exactly n times, but some steps skip printing due to continue.

How Execution Grows With Input

Even though some steps skip printing, the loop still checks every number.

Input Size (n)	Approx. Operations
10	10 checks, 5 prints
100	100 checks, 50 prints
1000	1000 checks, 500 prints

Pattern observation: The loop runs n times, but printing happens about half as often.

Final Time Complexity

Time Complexity: O(n)

This means the total work grows directly with the size of the input, even if some steps skip actions.

Common Mistake

[X] Wrong: "Since continue skips some steps, the loop runs fewer times and is faster."

[OK] Correct: The loop still checks every item; skipping only avoids some actions inside the loop, not the loop itself.

Interview Connect

Understanding how continue affects loops helps you explain code efficiency clearly and shows you know how loops behave in real situations.

Self-Check

What if we replaced continue with break? How would the time complexity change?

Practice

1. What does the continue statement do inside a loop in Python?

easy

A. Exits the current function

B. Stops the entire loop immediately

C. Skips the rest of the current loop iteration and moves to the next one

D. Repeats the current iteration without moving forward

Solution

1. Step 1: Understand the role of continue

   The continue statement tells the loop to skip the remaining code in the current iteration.

2. Step 2: Identify the loop behavior after continue

   After skipping, the loop moves to the next iteration without stopping the whole loop.

3. Final Answer:

   Skips the rest of the current loop iteration and moves to the next one -> Option C

4. Quick Check:

   continue skips current step [OK]

Hint: Remember: continue skips current step, break stops loop [OK]

Common Mistakes:

• Confusing continue with break
• Thinking continue exits the function
• Assuming continue repeats the iteration

2. Which of the following is the correct syntax to use continue inside a for loop?

easy

A. for i in range(5) { continue }

B. for i in range(5): continue

C. for i in range(5) continue

D. for i in range(5):
continue

Solution

1. Step 1: Check Python loop syntax

   Python requires a colon after the for statement and indentation for the loop body.

2. Step 2: Identify correct placement of continue

   continue must be inside the loop body, properly indented on the next line.

3. Final Answer:

   for i in range(5):\n continue -> Option D

4. Quick Check:

   Colon + indent + continue line [OK]

Hint: Use colon and indent for loop body with continue [OK]

Common Mistakes:

• Missing colon after for statement
• Writing continue on same line without colon
• Using braces {} which are not Python syntax

3. What is the output of this code?

for i in range(5):
    if i == 2:
        continue
    print(i)

medium

A. 0 1 3 4

B. 0 1 2 3 4

C. 2

D. 0 1

Solution

1. Step 1: Trace loop iterations and condition

   The loop runs i from 0 to 4. When i is 2, continue skips printing.

2. Step 2: List printed values

   Values printed are 0, 1, 3, and 4 because 2 is skipped.

3. Final Answer:

   0 1 3 4 -> Option A

4. Quick Check:

   continue skips i=2 print [OK]

Hint: Skip printing when continue triggers, others print [OK]

Common Mistakes:

• Including 2 in output
• Thinking continue stops loop
• Confusing continue with break

4. Find the error in this code snippet:

i = 0
while i < 5:
    if i == 3:
        continue
    print(i)
    i += 1

medium

A. Infinite loop because i is not incremented when i == 3

B. SyntaxError due to missing colon

C. Prints numbers 0 to 4 correctly

D. TypeError because of continue in while loop

Solution

1. Step 1: Analyze loop and continue effect

   When i equals 3, continue skips the rest, so i += 1 is not executed.

2. Step 2: Understand consequence

   Since i stays 3 forever, the loop never ends, causing an infinite loop.

3. Final Answer:

   Infinite loop because i is not incremented when i == 3 -> Option A

4. Quick Check:

   continue skips i++ causes infinite loop [OK]

Hint: Increment loop variable before continue or use else [OK]

Common Mistakes:

• Ignoring that continue skips increment
• Thinking continue causes syntax error
• Assuming loop ends normally

5. You want to print all numbers from 1 to 10 except multiples of 3 using a for loop and continue. Which code correctly does this?

hard

A. for i in range(1, 11):
if i % 3 == 0:
pass
else:
print(i)

B. for i in range(1, 11):
if i % 3 == 0:
continue
print(i)

C. for i in range(1, 11):
if i % 3 == 0:
break
print(i)

D. for i in range(1, 11):
if i % 3 != 0:
continue
print(i)

Solution

1. Step 1: Understand the goal

   We want to skip printing numbers divisible by 3, so use continue when i % 3 == 0.

2. Step 2: Check each option

   for i in range(1, 11): if i % 3 == 0: continue print(i) skips multiples of 3 correctly and prints others. for i in range(1, 11): if i % 3 != 0: continue print(i) skips non-multiples wrongly. for i in range(1, 11): if i % 3 == 0: break print(i) breaks loop early. for i in range(1, 11): if i % 3 == 0: pass else: print(i) uses pass but prints all except multiples of 3 correctly but without continue.

3. Final Answer:

   for i in range(1, 11): if i % 3 == 0: continue print(i) -> Option B

4. Quick Check:

   continue skips multiples of 3 print others [OK]

Hint: Use continue to skip unwanted cases inside loop [OK]

Common Mistakes:

• Using break instead of continue
• Reversing condition logic
• Not skipping multiples of 3