Here is the list of some of the good tutorials written by codeforces users :-
C++
- C++ Tricks by HosseinYousefi
- C++ STL: map and set by adamant

Data Structures
- Algorithm Gym :: Data Structures by PrinceOfPersia
- Everything about Segment Trees by PrinceOfPersia
- Efficient and easy Segtree by Al.Cash
- A simple introduction to "Segment tree beats" by jiry_2
- Sack(DSU on trees) by Arpa
- SQRT Tree by gepardo
- Link-Cut tree by adamant

DP
- DP on Trees by darkshadows
- SOS DP by usaxena95
- Recurrent Sequences — Application of combinatorics in DP by TooNewbie
- Non-trivial DP tricks & Techniques by zscoder

Math
- Invariants and monovariants by TooNewbie
- Mobius Inversion by Nisiyama_Suzune
- Dirichlet convolution by Nisiyama_Suzune
- Fast convolution for 64-bit integers by quasisphere
- Tutorial for FFT/NTT Part 1 by sidhant
- Tutorial for FFT/NTT Part 2 by sidhant
- On Fast Fourier Transform by adamant
- Extended Eratosthenes Sieve by lucyanna2018

String Processing
- Z algorithm by paladin8
- Suffix Automata by quasisphere
- Transition between Z- and prefix functions by adamant
- Manacher's algorithm and code readability by adamant

Geometry
- Quaternion algebra and geometry by adamant
- Slope Trick by zscoder
- Nearest Neighbor Search by P_Nyagolov
- Convex Hull trick and Li chao tree by adamant
- Geometry: 2D points and lines by Al.Cash
- Geometry: Polygon algorithms by Al.Cash

Graphs
- 0-1 BFS by himanshujaju
- 2-SAT by HosseinYousefi

Others
- Parallel Binary Search by himanshujaju
- General ideas and tricks by adamant

If you know some good tutorial on codeforces which is not in this list and another list provided below please mention it in the comments I will add that in the list.

Another Similar List
Good Blog Post Resources about Algorithm and Data Structures