ID	Title	Difficulty
56	Merge Intervals	Medium
59	Spiral Matrix II	Medium
60	Permutation Sequence	Medium
61	Rotate List	Medium
62	Unique Paths	Medium
63	Unique Paths II	Medium
64	Minimum Path Sum	Medium
71	Simplify Path	Medium
73	Set Matrix Zeroes	Medium
74	Search a 2D Matrix	Medium
75	Sort Colors	Medium
77	Combinations	Medium
78	Subsets	Medium
79	Word Search	Medium
80	Remove Duplicates from Sorted Array II	Medium
81	Search in Rotated Sorted Array II	Medium
82	Remove Duplicates from Sorted List II	Medium
86	Partition List	Medium
89	Gray Code	Medium
90	Subsets II	Medium
91	Decode Ways	Medium
92	Reverse Linked List II	Medium
93	Restore IP Addresses	Medium
94	Binary Tree Inorder Traversal	Medium
95	Unique Binary Search Trees II	Medium
96	Unique Binary Search Trees	Medium
98	Validate Binary Search Tree	Medium
102	Binary Tree Level Order Traversal	Medium
103	Binary Tree Zigzag Level Order Traversal	Medium
105	Construct Binary Tree from Preorder and Inorder Traversal	Medium