The Two-Pointer Technique: Reducing O(n²) to O(n) with Invariant-Based Pointer Movement

Short summary

A tutorial on the two-pointer technique for algorithm problems, using a Star Wars-themed narrative. Covers the container-with-most-water problem (O(n²) to O(n)) and three-sum, showing how starting pointers at opposite ends of a sorted array lets you greedily eliminate impossible pairs. Includes Python code for both brute-force and optimized solutions, plus common traps like updating max before moving pointers.

• •Two-pointer technique reduces O(n²) brute-force to O(n) by exploiting sorted invariants
• •Covers container-with-most-water and three-sum with Python code examples
• •Common traps: forgetting to update max before moving pointers or moving both at once

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