Two Pointers

Mindmap

Two Pointers

Two Heads for Two Arrays

one pointer per array

3-while merge

merge / alternate

Compare / match

subsequence, backspace

Direction

Same direction

read/write, subsequence

Opposite

palindrome, two-sum

Backward fill

merge from the end

Read / Write Heads

same array, in-place

Compaction

remove / dedup

Read scans, write keeps

Swap variant

removed move to back

Left / Right Heads

converge from the ends

Palindrome / compare

Reverse via swap

Sorted array

two-sum, squares

Partition

by parity

+

−

⟲

⛶

Problem Categories

Two Pointers

Read / Write Heads

same array, in-place

Compaction

remove / dedup

Read scans, write keeps

Swap variant

removed move to back

Left / Right Heads

converge from the ends

Palindrome / compare

Reverse via swap

Sorted array

two-sum, squares

Partition

by parity

Two Heads for Two Arrays

one pointer per array

3-while merge

merge / alternate

Compare / match

subsequence, backspace

Direction

Same direction

read/write, subsequence

Opposite

palindrome, two-sum

Backward fill

merge from the end

+

−

⟲

⛶