Array & string

for dirty problem, try a dirty example, then find out clue.

encode/decode

• 171. Excel Sheet Column Number
• 168. Excel Sheet Column Title
• 273. Integer to English Words
• 43. Multiply Strings

reverse

• 344. Reverse String (two pointers, divid-and-conquer)
• 189. Rotate Array
• 186. Reverse Words in a String II
• 151. Reverse Words in a String (dirty)
• 917. Reverse Only Letters

range

• 163. Missing Ranges (dirty)
• 228. Summary Ranges (dirty)
• 523. Continuous Subarray Sum (prefix sum and leverage reminder)

intersection

• 14. Longest Common Prefix
• 349. Intersection of Two Arrays (hash, binary search, two pointers)
• 350. Intersection of Two Arrays II (hash, binary search, two pointers)

matrix

• 73. Set Matrix Zeroes
• 48. Rotate Image
• 1428. Leftmost Column with at Least a One
• Spiral Matrix
  • 54. Spiral Matrix
  • 59. Spiral Matrix II
  • 885. Spiral Matrix III
• diagonal
  • 766. Toeplitz Matrix
  • 498. Diagonal Traverse
  • 1424. Diagonal Traverse II

read4

• 157. Read N Characters Given Read4
• 158. Read N Characters Given Read4 II - Call multiple times

array

• 277. Find the Celebrity
• 670. Maximum Swap
• 249. Group Shifted Strings

compress and decompress

• 38. Count and Say
• 394. Decode String

text justification

• 68. Text Justification

stack

• 227. Basic Calculator II
• 224. Basic Calculator
• 388. Longest Absolute File Path

propagation

• 1840. Maximum Building Height

Permutation

• 31. Next Permutation
• 1850. Minimum Adjacent Swaps to Reach the Kth Smallest Number
• 60. Permutation Sequence

Matching

• 777. Swap Adjacent in LR String

str to int

• 65. Valid Number
• 8. String to Integer (atoi)

Misc

• 287. Find the Duplicate Number (in-place modification, fast-slow pointers, binary search)
• 1146. Snapshot Array
• 755. Pour Water
• 336. Palindrome Pairs
• 1257. Smallest Common Region
• 1404. Number of Steps to Reduce a Number in Binary Representation to One
• 468. Validate IP Address
• 205. Isomorphic Strings