The two-pointer technique uses two indices to traverse an array from different ends or directions, allowing you to solve problems involving pairs, subarrays, or linked lists efficiently.

The two-pointer technique is a powerful approach in competitive programming that involves using two pointers to traverse a data structure, typically an array or linked list, from different directions. This technique is particularly useful in problems where you need to find pairs that satisfy a certain condition, such as finding two numbers in a sorted array that add up to a target sum. Instead of using nested loops, you can initialize one pointer at the beginning of the array and the other at the end. By comparing the sum of the elements at the two pointers, you can move one of the pointers closer to the other, depending on whether the sum is too large or too small. This reduces the time complexity from O(n^2) to O(n) for certain problems. The two-pointer technique can also be applied to problems involving subarrays, such as finding the longest subarray that meets a certain condition, or problems involving linked lists, like detecting cycles. By carefully managing the movement of the pointers, you can explore different parts of the array or list without needing extra loops or complex logic, making this technique both simple and efficient.