C code. C code run. Run code run… please!
Question: https://codility.com/demo/take-sample-test/distinct Question Name: Distinct In this question, the expected worst-case time complexity is O(N*log(N)). Thus the designed, or says official, solution would be sort the input and travel them. This solution is practically good. And it is shown as … Read More »
Before solving this problem, we introduce a simple library of stack with integers. Many following questions need an integer stack. Not to reinvent the wheel in our following solutions, we make a standalone integer stack library. Actually, we should do … Read More »
The first part of this question is easy: use a set of stacks to mimic a single stack. In the second part, we need to implement a new method as popAt(int index) to make a pop operation on a specific … Read More »
In my solution, I used a structure with two traditional stacks. One of them is used to store the original elements. The other is used to store the latest minimum elements. At any time, the top element in the second … Read More »
I used a different solution from the ones in the original book. In the first official solution in the book, one stack might be full while another is empty. The space utilization is bad. In the second official solution, once … Read More »
There is a similar and easier question: how to check if an array is a palindrome? Or equivalently, how to check if a double linked list is a palindrome? The three solutions in the original question work well for these … Read More »
There is a follow up question: how to determine whether two linked lists, to say list1 and list2, intersect each other. Two solutions are available for this problem. On one hand, we could link the end of list1 to the … Read More »
The official solution for the backward problem is quite good. In contrast, there are two improvable places in the official solution for the forward problem (the follow up question). On one hand, in the official implement, the list is double … Read More »
The question is one step in the quick sort algorithm. The idea is to rearrange the list so that the smaller nodes than pivot are previous to all other nodes. More details could be found on Wikipedia. In the implements … Read More »
The description of this question is not quite clear. What does “given only access to that node” exactly mean? If we cannot read any other node, it is impossible to finish the work. If we could only read the node, … Read More »