Medium Challenge

50 carefully selected medium difficulty problems covering diverse topics for systematic interview preparation.

50 道題目

#	題目	難度	Rating
1	18. 4Sum	Medium	1639
2	22. Generate Parentheses	Medium	1648
3	31. Next Permutation	Medium	1560
4	33. Search in Rotated Sorted Array	Medium	1625
5	34. Find First and Last Position of Element in Sorted Array	Medium	1483
6	36. Valid Sudoku	Medium	1422
7	39. Combination Sum	Medium	1469
8	40. Combination Sum II	Medium	1562
9	43. Multiply Strings	Medium	1499
10	45. Jump Game II	Medium	1618
11	47. Permutations II	Medium	1574
12	48. Rotate Image	Medium	1407
13	54. Spiral Matrix	Medium	1524
14	57. Insert Interval	Medium	1541
15	63. Unique Paths II	Medium	1400
16	71. Simplify Path	Medium	1532
17	73. Set Matrix Zeroes	Medium	1390
18	74. Search a 2D Matrix	Medium	1478
19	75. Sort Colors	Medium	1381
20	79. Word Search	Medium	1700
21	91. Decode Ways	Medium	1635
22	98. Validate Binary Search Tree	Medium	1490
23	103. Binary Tree Zigzag Level Order Traversal	Medium	1576
24	105. Construct Binary Tree from Preorder and Inorder Traversal	Medium	1643
25	114. Flatten Binary Tree to Linked List	Medium	1519
26	120. Triangle	Medium	1533
27	128. Longest Consecutive Sequence	Medium	1680
28	130. Surrounded Regions	Medium	1706
29	131. Palindrome Partitioning	Medium	1615
30	143. Reorder List	Medium	1532
31	148. Sort List	Medium	1636
32	152. Maximum Product Subarray	Medium	1555
33	153. Find Minimum in Rotated Sorted Array	Medium	1485
34	162. Find Peak Element	Medium	1536
35	167. Two Sum II - Input Array Is Sorted	Medium	1389
36	189. Rotate Array	Medium	1433
37	207. Course Schedule	Medium	1656
38	209. Minimum Size Subarray Sum	Medium	1445
39	210. Course Schedule II	Medium	1681
40	213. House Robber II	Medium	1608
41	236. Lowest Common Ancestor of a Binary Tree	Medium	1660
42	287. Find the Duplicate Number	Medium	1689
43	300. Longest Increasing Subsequence	Medium	1666
44	322. Coin Change	Medium	1684
45	416. Partition Equal Subset Sum	Medium	1624
46	424. Longest Repeating Character Replacement	Medium	1680
47	435. Non-overlapping Intervals	Medium	1567
48	560. Subarray Sum Equals K	Medium	1621
49	567. Permutation in String	Medium	1584
50	684. Redundant Connection	Medium	1597