The set [1,2,3,…,n] contains a total of n! unique permutations. By listing and labeling all of the permutations in order, We get the following sequence (ie, for n = 3 ) : “123” “132” “213” “231” “312” “321” Given n and k, return the kth permutation sequence. For example, given n = 3, k = 4, ans = “231”. There
Tag: data-structures
Sorting in java for array only containing 0 and 1
How to sort array Answer use any sorting algorithm to do it. For beginner use bubble sort (easy to understand) Refer Wiki EDITED As @Pradeep Said: You may definitely use Array.sort()
Get Minimum and maximum numbers from a list
Assuming we have a list containing integers and we need to find min & max. What is the best way to do it ? I can think of following : If number of reads are much higher than writes; keep the list in sorted manner. Whenever a number is added; add it in sorted manner. Now to get min and
Java Tree to represent filesystem (files/dir) from list of paths
I’ve a list of paths like this So from this list of paths (Stings) I need to crete a Java Tree structure that has folders as nodes and files as leaf (there wont be empty folders as leaf). What I need I think is the add method where I pass to them a String (path of the file) and it
Get keys from HashMap in Java
I have a Hashmap in Java like this: Then I fill it like this: How can I get the keys? Something like: team1.getKey() to return “United”. Answer A HashMap contains more than one key. You can use keySet() to get the set of all keys. will store 1 with key “foo” and 2 with key “bar”. To iterate over all
How to find the index of an element in a TreeSet?
I’m using a TreeSet<Integer> and I’d quite simply like to find the index of a number in the set. Is there a nice way to do this that actually makes use of the O(log(n)) complexity of binary trees? (If not, what should I do, and does anyone know why not? I’m curious why such a class would be included in
How do I instantiate a Queue object in java?
When I try: The compiler is giving me an error. Any help? Also, if I want to initialize a queue do I have to implement the methods of the queue? Answer A Queue is an interface, which means you cannot construct a Queue directly. The best option is to construct off a class that already implements the Queue interface, like
Why can hashCode() return the same value for different objects in Java?
A quote from the book I’m reading Head First Java: The point is that hashcodes can be the same without necessarily guaranteeing that the objects are equal, because the “hashing algorithm” used in the hashCode() method might happen to return the same value for multiple objects. Why might the hashCode() method return the same value for different objects? Does that
java: sparse bit vector [closed]
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. We don’t allow questions seeking recommendations for books, tools, software libraries, and more. You can edit the question so it can be answered with facts and citations. Closed 19 days ago. Improve this question Are there any well-known libraries in Java for sparse bit vectors?
Java implementation for Min-Max Heap?
Do you know of a popular library (Apache, Google, etc, collections) which has a reliable Java implementation for a min-max heap, that is a heap which allows to peek its minimum and maximum value in O(1) and to remove an element in O(log n)? Answer From Guava: MinMaxPriorityQueue.