# [Leetcode Pattern] - Array, String


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## Preface

Array and string topic can usually treated as the similar topic, so today we are 
going to learn the most common design pattern for those two topics.

## Two pointer

### Introduction

* Using two different pointer to frame out the current processing array while traversing the array

### When to use?

* Implement the various size sliding window

* Kadane's Algorithm: Iterative dynamic programming algorithm

## Sliding Window

### Introduction

* A range of frame to traverse the array

### When to use?

* Check for the count of the unique element contains in the frame

## Sorted Array

### Introduction

* Sort the array to the ascending/descending order.

### When to use?

* If the problem has stated that the array is sorted, you might have to consider whether there isn’t there binary search method or while traversing the array, you can optimize the scanning time by skipping the duplicated value.