• Two pointers: one input, opposite ends
• Two pointers: two inputs, exhaust both
• Sliding window
• Build a prefix sum
• Efficient string building
• Linked list: fast and slow pointer
• Reversing a linked list
• Find number of subarrays that fit an exact criteria
• Monotonic increasing stack
• Binary tree: DFS (recursive)
• Binary tree: DFS (iterative)
• Binary tree: BFS
• Graph: DFS (recursive)
• Graph: DFS (iterative)
• Graph: BFS
• Find top k elements with heap
• Binary search
• Binary search: duplicate elements, left-most insertion point
• Binary search: duplicate elements, right-most insertion point