Hi,
Drop some of your favorite problems which you think can educate us some new concept, tricks or ideas and we have a take away from those problems. :)
Please try to follow this particular format so that it is helpful for the readers (and also to me):
Probelm Rating (Eg: 1500) :
- Problem 1 (Why you recommend this problem)
- Problem 2 (Why you recommend this problem)
Probelm Rating 2 (Eg: 1600) :
- Problem 1 (Why you recommend this problem)
- Problem 2 (Why you recommend this problem)
You can also drop problems without following this xD. Just don't forget to drop some cool problems which we should definitely practice. :)
(https://codeforces.net/problemset/problem/1519/D)
Even Subarrays
1770C - Koxia and Number Theory 1801A - The Very Beautiful Blanket
Ya Best problem ever on codeforces to me
https://codeforces.net/contest/1731/problem/D DP/Prefix sums/Sparse table/Segment tree + binary search
Brothers, / equals or in my description, the problem is mostly solved with very easy techniques.
It is 1700 rated problem, why downvotes?
I Like the Problem mentioned above and recommend you all to solve both problems.
486E- LIS of Sequence
Good dp Problem. It will strengthen your concept of LIS.
https://codeforces.net/contest/1805/problem/D I think that's a really good problem because it greatly improves your bfs realisation skills. And it also includes a lot of concepts that are oftenly used in a lot of problems related to bfs/dfs. So i think it's a really great problem to practice on
Some problems that I really enjoyed solving and found enlightening. They made me very happy when I got AC:
1418C - Mortal Kombat Tower
977F - Consecutive Subsequence
699C - Vacations
1195C - Basketball Exercise
1234C - Pipes
580C - Kefa and Park
377A - Maze
277A - Learning Languages
131D - Subway
120F - Spiders
1574C - Slay the Dragon
1462E1 - Close Tuples (easy version)
1324D - Pair of Topics
924B - Three-level Laser
287B - Pipeline
1141D - Colored Boots
1082B - Vova and Trophies
815A - Karen and Game
550A - Two Substrings
1419C - Killjoy
1366C - Palindromic Paths
https://codeforces.net/contest/1594/problem/D A very great DSU problem
https://codeforces.net/problemset/problem/382/C
1734D — Slime Escape
a problem which took 7 months for me to upsolve
Air Conditioner — great DP
Pair of Topics — the 2 pointer trick is pretty neat
Most of my favorite problems are 2000 so I don't have much to share
Can you still share them?
SWERC 2021-2022 — Drone Photo
Too Many Impostors
Interacdive Problem
Letter Picking
Prefixes and Suffixes
These problems don't require any insane knowledge about DSA but more about making good observations, especially the impostors problem one, I think I solved that one when I was pupil. Other than that, I like most problem G about graph from the old div 3 contests, they are all very educational.
https://codeforces.net/contest/1373/problem/D
CF 1695C Zero Path
CF 1497 C2 k-LCM (hard version)
I like this one:
1699C — The Third Problem
Not the most creative name but its solution is satisfying.
Some problems are not <= 1700, but I think they are very interesting.
My favorite DP problems:
You can move rocks until they touch the border. Think about switching directions after every move and make move on a segment instead of one cell. Use prefix sums to get AC
There are 3 types of values of vaults: lower than k, k, bigger than k. Now think about how you can unite two subtrees using this information.
My favorite Graph problems: - 1675F - Vlad and Unfinished Business — Easy problem, but you need to think a bit to solve it
There are two types of verticies. Verticies which lead to thing and verticies which lead to Nastya. Now think about how to you use these verticies on tyour path.
I put this problem in Graph problems section on purpose. You can represent permurtation as cycles.
Think about storing masks in segment tree.
Other: - 455D - Serega and Fun — SQRT decomposition
Just use SQRT decomposition with rebuild after sqrt(n) operations. You can make cycle operation just by erasing and inserting values. Rebuild will provide this solution average of sqrt(n) complexitry on query.
My english is not very good so I could write something wrong.
1538D — Another Problem About Dividing Numbers
Because it's the first 1700 problem I solved during live contest. Also its a pretty cool number theory problem.
These are some of my favorite recent problems with rating 1300-1700.
1707A - Doremy's IQ
Recent problem.It is enough to learn digit dp well. 1808 C — Unlucky Numbers
C. Equal Frequencies -> 1600