Why Remove Duplicates from Sorted Array Two Pointer in DSA Python?

The Big Idea

What if you could clean a long list of duplicates in just one quick pass?

The Scenario

Imagine you have a long list of names sorted alphabetically, but some names appear more than once. You want to make a clean list with each name only once.

Doing this by checking each name one by one and removing duplicates manually is tiring and slow.

The Problem

Manually scanning the list and deleting duplicates means you have to move many names around each time you find a repeat.

This wastes time and can cause mistakes like skipping names or deleting the wrong one.

The Solution

The two-pointer method lets you scan the list just once, keeping track of unique names as you go.

One pointer moves through the list, the other marks where to place the next unique name.

This way, duplicates are skipped automatically, and the list is cleaned efficiently.

Before vs After

✗ Before

for i in range(len(names) - 1):
    if names[i] == names[i+1]:
        names.pop(i+1)

✓ After

unique_index = 0
for current_index in range(1, len(names)):
    if names[current_index] != names[unique_index]:
        unique_index += 1
        names[unique_index] = names[current_index]

What It Enables

This method makes it easy to clean sorted lists quickly, saving time and avoiding errors.

Real Life Example

When you get a sorted list of email addresses from a newsletter signup, you can quickly remove duplicates before sending emails.

Key Takeaways

Manual removal is slow and error-prone.

Two-pointer method scans once and keeps unique items.

Efficient and simple for sorted lists.