LeetCode
  • Introduction
  • Design
    • 348. Design Tic-Tac-Toe
    • 534. Design TinyURL
    • 535. Encode and Decode TinyURL
    • 346. Moving Average from Data Stream
    • 281. Zigzag Iterator
    • 381. Insert Delete GetRandom O(1) - Duplicates allowed
    • 432. All O`one Data Structure
    • 341. Flatten Nested List Iterator
    • 642. Design Search Autocomplete System
    • 170. Two Sum III - Data structure design
    • 622. Design Circular Queue
    • 295. Find Median from Data Stream
  • OOD
    • 146.LRU Cache(Amazon)
  • Sort
    • Bucket Sort
      • 791. Custom Sort String
      • 347. Top K Frequent Elements
      • 1057. Campus bikes
    • 280. Wiggle Sort
    • 75. Sort Colors
  • Binary Search
    • 278. First Bad Version
    • 162. Find Peak Element in O(logn)
    • LintCode 183. Wood Cut
    • 33. Search in Rotated Sorted Array
    • 81. Search in Rotated Sorted Array II
    • 153. Find Minimum in Rotated Sorted Array
    • 154. Find Minimum in Rotated Sorted Array II
    • 34. Find First and Last Position of Element in Sorted Array
    • Count number of occurrences (or frequency) in a sorted array
    • 378. Kth Smallest Element in a Sorted Matrix
    • 240. Search a 2D Matrix II
    • 658. Find K Closest Elements
    • 410. Split Array Largest Sum
  • Data Structure
    • Arrays
      • Two Pointer
        • 11. Container With Most Water
      • 283. Move Zeros
      • 26. Remove Duplicates from Sorted Array
      • 88. Merge Sorted Array
      • 683. K Empty Slots
      • 4. Median of Two Sorted Arrays
      • Interval
        • 56. Merge Interval
        • 57. Insert Interval
      • 54. Spiral Matrix
      • 48. Rotate Image(Amazon, MicroSoft, Apple)
      • 448. Find All Numbers Disappeared in an Array
      • 228. Summary Ranges
      • 289. Game of Life
      • 298. Product of Array Except Self
      • 825. Friends of Appropriate Ages
    • Stack
      • Postfix to Infix
      • 155. Min Stack
      • 716. Max Stack
      • 388. Longest Absolute File Path
      • 316. Remove Duplicate Letters
      • 636. Exclusive Time of Functions
      • Calculator Series
        • 227. Basic Calculator
        • 772. Basic Calculator III
    • Trie
      • 208. Implement Trie (Prefix Tree)
      • 211. Add and Search Word - Data structure design
      • 336. Palindrome Pairs
      • 212. Word Search II
    • Heap
      • 218. The Skyline Problem
      • 23. Merge k Sorted Lists
      • 252. Meeting Rooms
      • 253. Meeting Rooms II
      • 215. Kth Largest Element in an Array
      • 692. Top K Frequent Words
      • 373. Find K Pairs with Smallest Sums
    • Deque
      • 239. Sliding Window Maximum
    • Map
      • 128. Longest Consecutive Sequence
      • 350. Intersection of Two Arrays II
      • 760. Find Anagram Mappings
    • Segment Tree / Binary Indexed Tree
      • 308. Range Sum Query 2D - Mutable
      • 218. The Skyline Problem
      • 315. Count of Smaller Numbers After Self
      • 308. Range Sum Query 2D - Mutable
      • 493. Reverse Pairs
    • Linked List
      • 19. Remove Nth Node From End of List
      • 24. Swap Nodes in Pairs
      • 160. Intersection of Two Linked Lists
      • 138. Copy List with Random Pointer
      • 143. Reorder List
      • 445. Add Two Numbers II
    • Tree
      • BST
        • 109. Convert Sorted List to Binary Search Tree
        • 285. Inorder Successor in BST
        • Convert Binary Search Tree (BST) to Sorted Doubly-Linked List
        • Construct Binary Tree from Inorder and Postorder Traversal
      • 101. Symmetric Tree
      • 105. Construct Binary Tree from Preorder and Inorder Traversal
      • 106. Construct Binary Tree from Inorder and Postorder Traversal
      • 110. Balanced Binary Tree
      • 129. Sum Root to Leaf Numbers
      • 199. Binary Tree Right Side View
      • 257. Binary Tree Paths
      • 543. Diameter of Binary Tree
      • Sum Root to Leaf Numbers
    • Hash Table
      • 325. Maximum Size Subarray Sum Equals k
      • 314. Binary Tree Vertical Order Traversal
    • Union-Find
      • 721. Accounts Merge
      • 305. Number of Islands II
      • 323. Number of Connected Components in an Undirected Graph
      • 261. Graph Valid Tree
      • 947. Most Stones Removed with Same Row or Column
    • Linked List
      • 138. Copy List with Random Pointer
      • 21. Merge Two Sorted Lists
      • 23. Merge K Sorted Lists
      • 206. Reverse Linked List
      • 237. Delete Node in a Linked List
      • 141. Linked List Cycle
      • 142. Linked List Cycle II
      • 148. Sort List
      • 708. Insert into a Cyclic Sorted List
  • Graph
    • BFS/DFS
      • Topological Sort
        • 207. Course Schedule
        • 210. Course Schedule II
        • 133. Clone Graph
        • 675. Cut Off Trees for Golf Event
        • 269. Alien Dictionary
      • BackTracking
        • 39. Combination Sum
        • 40. Combination Sum II
        • 79. Word Search
        • 212. Word Search II
        • 282. Expression Add Operators
      • Memoization
        • 329. Longest Increasing Path in a Matrix
      • 733. Flood Fill
      • 279. Perfect Squares
      • 200. Number of Islands (Amazon)
      • 694. Number of Distinct Islands
      • 711. Number of Distinct Islands II
      • 98. Validate Binary Search Tree
      • 785. Is Graph Bipartite?
      • 491. Increasing Subsequences
      • 51. N-Queens
      • 52. N-Queens II
      • 286. Walls and Gates
      • 111. Minimum Depth of Binary Tree
      • 753. Craking the Safe
    • 399. Evaluate Division
    • 127. Word Ladder
    • 126. Word Ladder II
    • 339. Nested List Weight Sum
  • Traversal
    • 297. Serialize and Deserialize Binary Tree
    • 236. Lowest Common Ancestor of a Binary Tree
    • 235. Lowest Common Ancestor of a Binary Search Tree
    • 144. Binary Tree Preorder Traversal
    • 255. Verify Preorder Sequence in Binary Search Tree
    • 94. Binary Tree Inorder Traversal
    • 145. Binary Tree Post Order Traversal
    • 102. Level Order Traversal
    • 103. Binary Tree Zipzag Level Order Traversal
    • 107. Binary Tree Level Order Traversal
    • 156. Binary Upside Down
    • 173. Binary Search Tree Iterator
    • 99. Recover Binary Search Tree
    • Morris Traversal
    • 498. Diagonal Traverse
    • Flatten
      • Flatten Binary Tree to Linked List
  • Math
    • Bit Manipulation
      • 231. Power of Two
      • 393. UTF-8 Validation
      • 371. Sum of Two Integers
    • 463. Island Perimeter
    • 50. Pow(x,n)
    • 326. Power of Three
    • 67. Add Binary
    • 29. Divide Two Integers
    • 360. Sort Transformed Array
    • 247. Strobogrammatic Number II
    • 277. Find the Celebrity
    • 246. Strobogrammatic Number
    • 415. Add Strings
    • 398. Reservoir Sampling
    • 43. Multiply Strings
    • 311. Sparse Matrix Multiplication
    • 8. String to Integer (Atoi)
    • 7. Reverse Integer
    • 829. Consecutive Numbers Sum
    • MiniMax
      • Guess the Word
  • Sum
    • 1. Two Sum
    • 167. Two Sum II - Input array is sorted
    • 15. 3Sum
    • 16. 3Sum Closest
    • 18. 4Sum
    • 454. 4Sum II
    • Path sum
      • 124. Binary Tree Maximum Path Sum
      • 113. Path Sum II
      • 437. Path Sum III
    • 209. Minimum Size Subarray Sum
    • 862. Shortest Subarray with Sum at Least K
    • 560. Subarray Sum Equals K
    • 523. Continuous Subarray Sum
  • Parentheses
    • 20. Valid Parentheses
    • 32. Longest Valid Parentheses
    • 301. Remvoe Invalid Parenthesis
    • 678. Valid Parenthesis String
  • String
    • Substring Search
      • 3. Longest Substring Without Repeating Characters
      • 438. Find All Anagrams in a String
      • 76. Minimum Window Substring
      • 30. Substring with Concatenation of All Words
      • 159. Longest Substring with At Most Two Distinct Characters
      • 340. Longest Substring with At Most K Distinct Characters
      • 395. Longest Substring with At Least K Repeating Characters
    • 12. Integer to Roman
    • 13. Roman to Integer
    • 44. Wildcard Matching
    • 242. Valid Anagram
    • 49. Group Anagrams
    • 657. Judge Route Circle
    • 482. License Key Formatting
    • 681. Next Closet Time
    • 387. First Unique Character in a String
    • 426. Convert Binary Search Tree to Sorted Doubly Linked List
    • 273. Integer to English Words
    • 157. Read N Characters Given Read4
    • 158. Read N Characters Given Read4 II - Call multiple times
    • 480. Valid Word Abbreviation
    • 409. Longest Palindrome
    • 680. Valid Palindrome II
    • 125. Valid Palindrome
    • 468. Validate IP Address
    • 161. One Edit Distance
    • 38. Count and Say
    • 1096. Brace Expansion II
  • Greedy
    • 630. Course Schedule III
    • 621. Task Scheduler
    • 358. Rearrange String k Distance Apart
    • 406. Queue Reconstruction by Height
    • 316. Remove Duplicate Letters
    • 767. Reorganize String
  • Dynamic Programming
    • Palindromic Substring
      • 5. longest Palindromic Substring
    • Subarray
      • 53. Maximum Subarray
      • 152. Maximum Product Subarray
    • Backpack problem
      • Backpack I
      • Backpack II
      • Backpack III
      • Backpack IV
      • Backpack V
      • Backpack VI aka: Combination Sum IV
      • Coin Change 2
    • 70. Climbing Stairs
    • 10. Regular Expression Matching
    • 91. Decode Ways
    • 338. Counting Bits
    • 121. Best Time to Buy and Sell Stock
    • 122. Best Time to Buy and Sell Stock II
    • 123. Best Time to Buy and Sell Stock III
    • 139. Word Break
    • 140. Word Break II
    • 198. House Robber
    • 72. Edit Distance
    • 221. Maximal Square
    • 84. Largest Rectangle in Histogram
    • 312. Burst Balloons
    • 304. Range Sum Query 2D - Immutable
    • 518. Coin Change 2
    • Longest Arithmetic Progression
    • 975. Odd Even Jump
    • 1066. Campus Bikes II
  • JingChi.ai
    • Word Composition
    • Sliding Window Median
    • 537. Erect the Fence (Convex Hull Problem)
    • LintCode 558: Sliding Window Matrix Maximum
    • orienteering game
    • 扫雷
  • Twitter
    • Identifying Triangle
    • Last and Second-Last
    • 300. Longest increasing subsequence
    • Twin String
    • 647. Number of palindromic substring
    • Wildcard Matching
  • Akuna
    • C++ Intern
    • V1
    • V2
    • Cut the Sticks
    • Quant Dev
    • Postfix_to_infix
    • Drone Delivery
    • phone
  • LintCode Contest
    • Ask For Cooling Time
  • SQL
    • 176. Second Highest Salary
    • 597. Friend Requests I: Overall Acceptance Rate
  • FB 19
    • Convert Binary Search Tree (BST) to Sorted Doubly-Linked List
    • 3Sum
    • Minimum Window Substring
    • Count number of occurrences (or frequency) in a sorted array
    • Count NO2
    • Valid Palindrome
    • Merge k Sorted Lists
    • Kth Largest Element in an Array
    • Move Zeros
    • Remove Invalid Parenthesis
    • friends
    • Integer to English
    • Islands
    • Valid Palindrome
    • sec
      • Longest Increasing Path in a Matrix
      • Product of Array Except Self
      • Binary Tree Vertical Order Traversal
      • Add Binary
      • Valid Parentheses
      • sup
        • 128. Longest Consecutive Sequence
        • Combination Sum II
        • Add and Search Word - Data structure design
        • feb
  • Google 20
    • 410. Split Array Largest Sum
  • 818. Race Card
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Last and Second-Last

找到字符串和倒数第二个字符， 用whitespace 隔开

解法： 直接判断最后一个和倒数第二个字符存不存在，存在就输出。

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