Solution to Rectangle-Builder-Greater-Area by codility

20 Nov

Question: https://codility.com/demo/take-sample-test/rectangle_builder_greater_area/ Question Name: Rectangle-Builder-Greater-Area or RectangleBuilderGreaterArea This key is the binary search.

Solution to Dwarfs-Rafting by codility

19 Nov

Question: https://codility.com/demo/take-sample-test/dwarfs_rafting/ Question Name: Dwarfs-Rafting or DwarfsRafting Need some simple mathematical knowledge. The code is unnecessarily long. A 2-d array is better to write much shorter code. However, I keep the long version for better readability.

Solution to Slalom-Skiing by codility

22 Oct

Question: https://codility.com/programmers/lessons/90-tasks_from_indeed_prime_2015_challenge/slalom_skiing/ Question Name: Slalom-Skiing or SlalomSkiing This is a wonderful variant of longest increasing subsequence. Because the longest increasing subsequence is a very classic question withe O(NlogN) solution, the key point to solve this question is to covert its original form … Read More »

Solution to Flood-Depth by codility

25 Sep

Question: https://codility.com/demo/take-sample-test/flood_depth/ Question Name: Flood-Depth or FloodDepth This is a variant of Trapping Rain Water by LeetCode. The undergoing concept is the same. However, the implementation is a bit different.

22 Sep

Solution to Sql-Sum by codility

21 Sep

Question: https://codility.com/demo/take-sample-test/sql_sum/ Question Name: Sql-Sum or SqlSum This question is too easy to be a serious training lesson. Most likely, it’s a live test for SQL challenges on Codility.com. The following solution works in both PostgreSQL and SQLite.

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 second solution is using sorting. We could sort the input and check each 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 recursion 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. Shortest Palindrome by adding any characters in the head.  Therefore the original string “original” is going … Read More »