The Two Pointers technique is a pattern that uses two pointers to solve problems efficiently. These pointers typically move through an array or linked list in a specific way to find a solution. The main idea is to have a left pointer and a right pointer, both starting at different indices of the array.

Let's look at a classic example of the Two Pointers technique: the "Two Sum II" problem. In this problem, we're given a sorted array of integers and a target sum. We need to find two numbers in the array that add up to the target sum.

class Solution:
    def twoSum(self, numbers: List[int], target: int) -> List[int]:
        # Step 1: Initialize two pointers
        left, right = 0, len(numbers) - 1
        
        # Step 2: Move the pointers
        while left < right:
            # Step 3: Compare and process
            total = numbers[left] + numbers[right]
            if total < target:
                left += 1 
            elif total > target:
                right -= 1 
            # Step 4: Terminate (solution found)
            else:
                return [left + 1, right + 1]  
        
        # Step 4: Terminate (when loop ends)
        return []

In this example, we start with two pointers: left at the beginning of the array and right at the end. We move these pointers based on whether the current sum is less than, equal to, or greater than the target sum. This approach works because the array is sorted, allowing us to efficiently narrow down the search space.

Understanding the Two Pointers technique is important for solving many coding interview problems efficiently. These best practices will help you implement this technique effectively and avoid common pitfalls: