Two Pointers: Introduction

About the pattern

The two pointers pattern is a versatile technique used in problem-solving to efficiently traverse or manipulate sequential data structures, such as arrays or linked lists. As the name suggests, it involves maintaining two pointers that traverse the data structure in a coordinated manner, typically starting from different positions or moving in opposite directions. These pointers dynamically adjust based on specific conditions or criteria, allowing for the efficient exploration of the data and enabling solutions with optimal time and space complexity. Whenever there’s a requirement to find two data elements in an array that satisfy a certain condition, the two pointers pattern should be the first strategy to come to mind.

The pointers can be used to iterate through the data structure in one or both directions, depending on the problem statement. For example, to identify whether a string is a palindrome, we can use one pointer to iterate the string from the beginning and the other to iterate it from the end. At each step, we can compare the values of the two pointers and see if they meet the palindrome properties.