BUD

• B: Bottleneck. The option which has the largest O(). Try to reduce the time complexity of this step.
• U: Unnecessary work. Chop branches.
• D: Duplicated work. Use remember table to solve it.

DIY

• Give yourself a big example.
• Solve it intuitively.
• Abstract your solution to solve the algorithm problem.

Simplify and Generalize

Downcast the problem to a easier one. e,g,: String --> Character

Base case and Build

Calculate from n=1.
When calcultate n=2, check whether can based on n=1 result.
When calculate n=3, check n=2, n=1 result. ----------This type is often recursive.

Data Structure Brainstorm

• Linked List: easy modify, hard search
• Array: easy search, hard modify
• Binary Tree: Binary search tree
• Heap: min, max, median(maintain 2 heaps)
• Priority Queue: maintain sorted
• Stack: push and pop, same sequence
• Hash Table: deal with unsorted array
• Map: Key-Value, Hashmap