🛠 Two Pointers Pattern: Spot It & Solve Fast

When to use: Sorted arrays, find pairs, or remove duplicates.
Simple Template:

left, right = 0, len(arr)-1
while left < right:
    if condition(arr[left], arr[right]):
        # found or move both
        left += 1
        right -= 1
    elif too_small:
        left += 1
    else:
        right -= 1

Interviewer:

Tell me if two numbers in a sorted array sum to target" (Two Sum II) or "Container With Most Water.

How to Answer:

Array is sorted, so two pointers from ends should work in O(n)

Show brute force first, then optimize. Practice: 3Sum, Remove Duplicates.

🔥 You will solve these in <15 mins next interview!