The two-pointer technique is an approach used to solve problems on arrays or lists by using two indices (pointers) that move through the data structure, usually from opposite ends or sometimes the same direction, depending on the problem.

Why use two pointers?
1). To reduce the time complexity compared to nested loops (which are O(n²)).

2). To efficiently search for pairs, triplets, or intervals satisfying a certain condition.

3). To avoid extra space usage by working directly on the input array.

Common scenarios for two-pointer:
1). Finding pairs with a sum (Two Sum in sorted array)

2). Removing duplicates or partitioning arrays

3). Merging two sorted arrays

4). Trapping rain water problem

5). Reversing arrays or strings