notes/OJ notes/pages/Two pointers approach.md

# Two pointers approach

#### 2022-06-14 23:06

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##### Algorithms:

#algorithm #two_pointers

##### Data structures:

#array #linked_list

##### Difficulty:

#CS_analysis

##### Related problems:

##### Links:

- [leetcode](https://leetcode.com/explore/learn/card/fun-with-arrays/511/in-place-operations/)
- [Two-pointers and sliding windows](https://leetcode.com/problems/subarray-sum-equals-k/discuss/301242/General-summary-of-what-kind-of-problem-can-cannot-solved-by-Two-Pointers)

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### What is Two pointers approach?

By using two pointers, to in place modify array elements.

- One fast and one slow [[Leetcode Best-Time-To-Buy-And-Sell-Stock]] or [[Leetcode Linked-List-Cycle]]
- The two are unordered [[Leetcode Merge-Two-Sorted-Lists]]

### Why and when to use it?

- There are two arrays, or linked lists
- They are sorted, or operation in place will not interfere elements after.

### When not use it?

Refer to [this link](https://leetcode.com/problems/subarray-sum-equals-k/discuss/301242/General-summary-of-what-kind-of-problem-can-cannot-solved-by-Two-Pointers)

#TODO: complete this section