## Solution to Contains Duplicate by LeetCode

20 Aug

Question: https://leetcode.com/problems/contains-duplicate/ Question Name: Contains Duplicate In general, I found two solutions. The first solution is using hash set:

The secondÂ solution is using sorting. We could sort the input and check eachÂ pair of adjacent items. Or we could early … Read More »

## Solution to Combination Sum III by LeetCode

15 Aug

Question: https://leetcode.com/problems/combination-sum-iii/ Question Name: Combination Sum III This is a typical recursionÂ problem. Find out the base case and recursive cases, and that’s the right solution.

## Solution to Kth Largest Element in an Array by LeetCode

10 Jun

Question: https://leetcode.com/problems/kth-largest-element-in-an-array/ Question Name: Kth Largest Element in an Array This is exactly the quick-select.

## Solution to Shortest Palindrome by LeetCode

8 Jun

Question: https://leetcode.com/problems/shortest-palindrome/ Question Name: Shortest Palindrome This is a variant of Longest Palindromic Substring. The key point is to convert the original question as following: 1.Â Shortest Palindrome by adding any characters in the head. Â Therefore the original string “original”Â is going … Read More »

## Solution to House Robber II by LeetCode

3 Feb

Question: https://leetcode.com/problems/house-robber-ii/ Question Name: House Robber II This is a variant of House Robber. We need to apply the previous solution to two sub-arrays and return the maximum of the two results: 1. Do not use the first element, and … Read More »

## Solution to Word Search II by LeetCode

1 Feb

Question: https://leetcode.com/problems/word-search-ii/ Question Name: Word Search II In general, this is a question with DFS/BFS of graph. Additionally, we need some optimizations: Use prefix tree to terminate the search early; Remove the found word in the prefix tree; Use bigrams … Read More »

## Solution to Add and Search Word – Data Structure Design by LeetCode

8 Jan

Question: https://leetcode.com/problems/add-and-search-word-data-structure-design/ Question Name: Add and Search Word – Data Structure Design This is a variant of prefix tree (trie).

## Solution to Course Schedule II by LeetCode

3 Jan

Question: https://leetcode.com/problems/course-schedule-ii/ Question Name: Course Schedule II

## Solution to Minimum Size Subarray Sum by LeetCode

1 Jan

Question: https://leetcode.com/problems/minimum-size-subarray-sum/ Question Name: Minimum Size Subarray Sum This question is very similar with Longest Substring Without Repeating Characters and Minimum Window Substring.

## Solution to Implement Trie (Prefix Tree) by LeetCode

1 Jan

Question: https://leetcode.com/problems/implement-trie-prefix-tree/ Question Name: Implement Trie (Prefix Tree) Not a full implementation. The delete function is not required.