Hard

Problem	Pattern	Lists	Description
Merge K Sorted Lists	Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort	Blind 75, Grind 75, Grind 169, NeetCode 150, Google Top 50	You are given an array of k linked-lists lists, each linked-list is sorted in ascending order. Merge all the
Minimum Window Substring	Hash Table, String, Sliding Window	Blind 75, Grind 75, Grind 169, NeetCode 150	Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every
Sliding Window Maximum	Array, Queue, Sliding Window, Heap (Priority Queue), Monotonic Queue	Grind 169, NeetCode 150, Amazon Top 50	You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the
Trapping Rain Water	Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack	Grind 75, Grind 169, NeetCode 150, Amazon Top 50, Google Top 50	Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it