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LeetCode
  • Overview
  • Mixed / Design
    • Two Sum (4 Qs)
      • 0001. Two Sum
      • 0167. Two Sum II - Input array is sorted
      • 0170. Two Sum III - Data structure design
      • 0653. Two Sum IV - Input is a BST
    • 0015. 3Sum
    • 0208. Implement Trie (Prefix Tree)
  • String
    • 0014. Longest Common Prefix
    • 0028. Implement strStr()
    • 0344. Reverse String
    • 0151. Reverse Words in a String
    • 0557. Reverse Words in a String III
    • 0067. Add Binary
    • 0415. Add Strings
    • 0038. Count and Say
    • 0394. Decode String
    • 0953. Verifying an Alien Dictionary
    • 0020. Valid Parentheses
  • Linked List
    • 0002. Add Two Numbers
    • 0445. Add Two Numbers II
    • 0021. Merge Two Sorted Lists
    • 0023. Merge k Sorted Lists
    • 0206. Reverse Linked List
    • 0019. Remove Nth Node From End of List
  • Tree
    • 0098. Validate BST
    • 0100. Same Tree
    • 0101. Symmetric Tree
    • 0226. Invert Binary Tree
    • 0110. Balanced Binary Tree
    • 0250. Count Univalue Subtrees
    • 0654. Maximum Binary Tree
    • Binary Tree Traversal (7 Qs)
      • 0144. Preorder Traversal
      • 0145. Postorder Traversal
      • 0094. Inorder Traversal
      • 0102. Level Order Traversal
      • 0104. Maximum Depth
      • 0111. Minimum Depth
      • 1302. Deepest Leaves Sum
      • 0993. Cousins in Binary Tree
    • N-ary Tree Traversal (4 Qs)
      • 0589. Preorder Traversal
      • 0590. Postorder Traversal
      • 0429. Level Order Traversal
      • 0559. Maximum Depth
    • Convert to BST (2 Qs)
      • 0108. Convert Sorted Array to Binary Search Tree
      • 0109. Convert Sorted List to Binary Search Tree
  • Binary Search
    • 0704. Binary Search
    • 0035. Search Insert Position
    • 0278. First Bad Version
    • 0367. Valid Perfect Square
    • 0069. Sqrt(x)
    • 0875. Koko Eating Bananas
    • 1011. Capacity To Ship Packages Within D Days
    • 0410. Split Array Largest Sum
    • 0004. Median of Two Sorted Arrays
  • Two Pointer
    • 0075. Sort Colors
    • 0088. Merge Sorted Array
    • 0283. Move Zeroes
    • 0125. Valid Palindrome
    • 0011. Container With Most Water
    • 0026. Remove Duplicates from Sorted Array
  • Sliding Window
    • 0003. Longest Substring Without Repeating Characters
  • Sorting
    • 0148. Sort List
    • 0912. Sort an Array
    • 0215. Kth Largest in Array
  • Dynamic Programming
    • 0509. Fibonacci Number
    • 1137. N-th Tribonacci Number
    • 0055. Jump Game
    • 0053. Maximum Subarray
    • 0022. Generate Parentheses
    • 0005. Longest Palindromic Substring
    • 0072. Edit Distance
    • Buy and Sell Stock (6 Qs)
      • 0122. Best Time to Buy and Sell Stock II
      • 0714. Best Time to Buy and Sell Stock with Transaction Fee
      • 0121. Best Time to Buy and Sell Stock
      • 0309. Best Time to Buy and Sell Stock with Cooldown
      • 0123. Best Time to Buy and Sell Stock III
      • 0188. Best Time to Buy and Sell Stock IV
  • DFS / BFS
    • 0200. Number of Islands
  • Math
    • 0007. Reverse Integer
    • 0009. Palindrome Number
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  1. Mixed / Design

Two Sum (4 Qs)

Series of problems related to "Two Sum"

PreviousOverviewNext0001. Two Sum

Last updated 3 years ago

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This question is kind of the classic problem in LeetCode. Though it seems like a pretty easy question, through its extension, we could learn a lot.

Related problems (follow the order to solve each problem):

  • Hash Table

  • Two Pointer

  • Binary Search

  • Binary Search Tree + Stack

0001. Two Sum
0167. Two Sum II - Input array is sorted
0170. Two Sum III - Data structure design
0653. Two Sum IV - Input is a BST