Solidity stdlib is a collection of core tools such as data structures, algorithms, helper functions, etc.
Each project is linked as-is, at no particular order. listings are not to be interperted as endorsments, do your own research and use on your own discretion.
Linked List by brockelmore/memmove
Linked List by vitruvius
Linked List Stack by d3or
Doubly Linked List by brockelmore/memmove
Doubly Linked List by morpho-dao
(tutorial) Linked List by Austin Griffith
Queue by faheelsattar
Linked List Stack by d3or
Stack by vitruvius
Heap by morpho-dao
Heap Ordering* by morpho-dao (*require clarification: what is the difference between normal heap and this?)
Mapping by brockelmore/memmove
Binary Tree by d3or
Red-Black Binary-Tree by bokkypoobah
Red-Black Binary-Tree by morpho-dao
Red-Black Binary-Tree by Polygon
Optimized Red-Black Tree by morpho-dao
K-Array Tree by volt-protocol
https://github.com/brockelmore/memmove
includes: array, linked list, doubly linked list, mapping, json
https://github.com/aunyks/vitruvius
includes: linked list, stack
https://github.com/morpho-dao/morpho-data-structures
includes: doubly linked list, heap, red black binary tree
https://github.com/firoorg/solidity-BigNumber
Various Algorithms by TheAlgorithms
includes: bubble sort, selection sort, binary search, various math utils