LeetCode 493: Reverse Pairs
A clear explanation of counting pairs where nums[i] is greater than twice nums[j] using merge sort.
Tag
Binary-Indexed-Tree
4 notes
LeetCode 315: Count of Smaller Numbers After Self
A clear explanation of Count of Smaller Numbers After Self using coordinate compression and a Fenwick Tree.
LeetCode 308: Range Sum Query 2D - Mutable
A clear explanation of Range Sum Query 2D - Mutable using a 2D Fenwick Tree for efficient updates and rectangle sum queries.
LeetCode 307: Range Sum Query - Mutable
A clear explanation of Range Sum Query - Mutable using a Fenwick Tree for efficient updates and range sums.