Problems
Counting Neighbors#11861
Medium · Hashing
Maximize your Balance#11860
Easy · Greedy algorithms · Sorting
Triangular Summation#11863
Very hard · Prefix Sums · Math · Queries
AND OR XOR#11862
Hard · Bitwise Operations · Greedy algorithms · Two pointers · Prefix Sums
Non-Cat-Rinks#11864
Very hard · Trees · Greedy algorithms · Segment Tree · Data Structures · Range queries · Sorting