NeetCode 150, Hard problems

Hard problems

All 22 hard problems in the NeetCode 150, grouped by pattern category. Each link points at the same problem page used in the category lists.

Two Pointers

• 42. Trapping Rain Water (Hard)

Sliding Window

• 76. Minimum Window Substring (Hard)
• 239. Sliding Window Maximum (Hard)

Stack

• 84. Largest Rectangle in Histogram (Hard)

Binary Search

• 4. Median of Two Sorted Arrays (Hard)

Linked List

• 23. Merge k Sorted Lists (Hard)
• 25. Reverse Nodes in k-Group (Hard)

Trees

• 124. Binary Tree Maximum Path Sum (Hard)
• 297. Serialize and Deserialize Binary Tree (Hard)

Tries

• 212. Word Search II (Hard)

Heap / Priority Queue

• 295. Find Median from Data Stream (Hard)

Backtracking

• 51. N-Queens (Hard)

Intervals

• 1851. Minimum Interval to Include Each Query (Hard)

Graphs

• 127. Word Ladder (Hard)
• 269. Alien Dictionary (Hard)

Advanced Graphs

• 332. Reconstruct Itinerary (Hard)
• 778. Swim in Rising Water (Hard)

2-D Dynamic Programming

• 10. Regular Expression Matching (Hard)
• 72. Edit Distance (Hard)
• 115. Distinct Subsequences (Hard)
• 312. Burst Balloons (Hard)
• 329. Longest Increasing Path in a Matrix (Hard)

Related

• Easy problems (28 problems)
• Medium problems (99 problems)
• LeetCode 150 (NeetCode) (full topic)