Problems
Digital Clock#4025
Easy · Implementation · Brute force
Edge Case#4026
Medium · Combinatorics · Dynamic programming
Guards#4028
Easy · Graphs
Hip To Be Square#4029
Easy · Math · Brute force
Idol#4030
Very easy · 2-SAT
Joint Venture#4031
Easy · Binary Search · Sorting
Key Insight#4032
Hard · Combinatorics · Sorting · Strings
Tram#4033
Very easy · Stacks
Minimum and Maximum in a tree#4034
Easy · Trees · Binary Search
Ice-Cream#4035
Medium · Binary Search · Greedy algorithms
Pre-Order Traversal of a Tree#4036
Very easy · Binary Search
Merge Sort#4037
Easy · Sorting
Post-Order Traversal of a Tree#4038
Very easy · Binary Search · Trees
Heap it!#4039
Very easy · Data Structures
Factor Trees#4040
Very easy · Sorting · Math
Commercial Calculator#4041
Easy · Greedy algorithms · Priority Queue
Median of Unions#4042
Medium · Sorting · Binary Search
Roses#4043
Hard · Math
N Queens#4044
Medium · Brute force
Brackets#4045
Very hard · Dynamic programming
Mobile#4046
Very hard · Binary Search
Peaks#4047
Hard · Graphs · Disjoint set union · Sorting · Greedy algorithms
Fireworks in RightAngleles#4048
Very hard · Greedy algorithms
Melody#4049
Very hard · Dynamic programming
Strategic Game#4050
Easy · Games · Graphs · Depth-first Search