Problems

Easy · Trees · Depth-first Search · Prefix Sums

Very hard · Segment Tree · Greedy algorithms · Dynamic programming

Easy · Segment Tree · Range queries

Very easy · Brute force

Medium · Combinatorics · Number theory · Brute force

Very easy · Greedy algorithms · Sorting · Implementation

Hard · Meet-in-the-middle · Hashing · Strings

Medium · Brute force · Number theory · Combinatorics

Hard · Sorting · Two pointers · Greedy algorithms · Binary Search

Hard · Breadth-first Search · Dynamic programming · Shortest paths · Sorting · Graphs

Hard · Dynamic programming · Prefix Sums

Hard · Greedy algorithms · Sorting · Data Structures

Medium · Strings · Stacks

Very easy · Prefix Sums · Greedy algorithms

Medium · Dynamic programming

Easy · Strings · Prefix Function · Data Structures · Stacks

Medium · Dynamic programming

Easy · Greedy algorithms · Priority Queue · Graphs

Easy · Dynamic programming · Fenwick Tree · Data Structures · Prefix Sums

Hard · Strings · Hashing · Data Structures

Very hard · Divide and Conquer · Convex Hull · Data Structures

Very easy · Brute force

Hard · Greedy algorithms · Graphs · Shortest paths

Very easy · Binary Search · Math · Two pointers

Medium · Bitmasks · Brute force · Shortest paths