This is a directory of solutions to competitive programming problems I have solved over the past 2-3 years. Many of the Olympiad problems can be found at https://oichecklist.pythonanywhere.com/, a great resource for preparation. My personal checklist is https://oichecklist.pythonanywhere.com/view/a6136b008a39e40653ead18ee8dc7aa986d1acb3.
There are a few solutions that I attempted in contest and did not upsolve, and therefore may be incomplete.
AGM: Adolescent Grigore Moisil International Programming Contest (https://codeforces.com/gym/102968)
APIO: Asia Pacific Informatics Olympiad (problems available at https://oj.uz/)
AtCoder: https://atcoder.jp/
BOI: Baltic Olympiad in Informatics (problems available at https://cses.fi/)
CodeChef: https://www.codechef.com/
GCJ: Google Code Jam (https://codingcompetitions.withgoogle.com/codejam)
HackerRank: https://www.hackerrank.com/
IARCS: https://www.iarcs.org.in/inoi/online-study-material/problems/
IOI: International Olympiad in Informatics (https://ioinformatics.org/, problems available at https://oj.uz/)
IOITC: IOI Training Camp India (problems are not publicly available)
IZhO: International Zhautykov Olympiad in Informatics (problems available at https://codeforces.com/ and https://oj.uz/)
Innopolis: Innopolis Open (https://2020.olymp.innopolis.ru/informatics)
JOI: Japanese Olympiad in Informatics (problems available at https://oj.uz/)
POI: Polish Olympiad in Informatics (problems available at https://szkopul.edu.pl/)
SPOJ: https://www.spoj.com/
UFDS: Problem setting and testing for personal contest
USACO: http://usaco.org/
UVa: https://onlinejudge.org/
mBIT: Montgomery Blair Informatics Tournament (https://mbit.mbhs.edu/)