binary-search | 易学教程

Difficulty with Collections.binarySearch

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问题 I am new to JAVA and Netbeans and this is what I have to do: The user can write a CD title in the input box and then remove the CD from the list by pressing the remove button. If the CD does not exist in the collection, then a message can be displayed in the outbox to state this. I have to use Collections.binarySearch() to do this. This is only a part of the whole program but I already figured out the rest of it. This is what I have done: ArrayList <String> songs = new ArrayList();

Check if a number exists in a given set of ranges

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Suppose we have a set of N ranges, (A1, B1) (A2, B2) (A3, B3) ... (An, Bn), where Ai denotes the starting point and Bi denotes the ending point of a range. (Ai, Bi are positive integers) How do we check using Binary Search if the given integer, say X, exists in at least one of the N ranges? My approach: Sort the ranges by x-coordinate first and then by y-coordinate. Find the smallest x-coordinate greater or equal to X. Check if that range is satisfied. If yes, we have a solution. Now, if that range doesnt contain X, what should be my next step? Or, should the solution be entirely different?

making binary search tree

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问题 How do I make a BST when I have an array list of 100 elements like {3,2,6,7,...,99} ? 回答1: I believe TreeSet is an implementation of a binary search tree. Since integers have a natural ordering you could simply loop through your array of integers and add them all to a TreeSet<Integer> . Note also, that there is a method Arrays.binarySearch that does a binary search in a sorted array. int[] someInts = {3,2,6,7, /*...,*/ 99}; // use a TreeSet TreeSet<Integer> ints = new TreeSet<Integer>(); for

How to find the first smaller element than an integer X in a vector ? (c++)

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问题 If I have the following vector {10 10 10 20 20 20 30 30} and I want a function to return the position of the integer that = X or directly the smaller element after X , like for example if I am searching for 11 I want the function to return 2 since the 2nd element(10) is the first smaller element than 11 in the vector. I tried using lower_bound but that doesn't work. int myints[] = {10,20,30,30,20,10,10,20}; vector<int> v(myints,myints+8); // 10 20 30 30 20 10 10 20 vector<int>::iterator low

Why is Collections.binarySearch giving wrong results?

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I have created a List where I have kept some strings. But when I am doing binary search within this list, it is returning negative values while the item is in the list . So far my knowledge positive value will be returned when item in the list . But for some items it is returning negative and for some items positive. Code: @Test public void hello() { // List<String> arlst = new ArrayList<String>(); List arlst = new ArrayList(); arlst.add("TP"); arlst.add("PROVIDES"); arlst.add("QUALITY"); arlst.add("TUTORIALS"); arlst.add("Stop"); arlst.add("StopP"); for (Iterator<String> iterator = (Iterator

Array of undefinite length [closed]

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It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center . Closed 9 years ago . how to find a random element in a sorted array of unknown length. I'll assume you mean how do I find if an element is part of the array? not how do I return a random element from the array? . Use binary search and assume that the length is very big (surely you have an upper bound?). If the middle element m you

Binary search over a huge file with unknown line length

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I'm working with huge data CSV file. Each file contains milions of record , each record has a key. The records are sorted by thier key. I dont want to go over the whole file when searching for certian data. I've seen this solution : Reading Huge File in Python But it suggests that you use the same length of lines on the file - which is not supported in my case. I thought about adding a padding to each line and then keeping a fixed line length , but I'd like to know if there is a better way to do it. I'm working with python You don't have to have a fixed width record because you don't have to

Binary Search solution for Max Number of Surpassers

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问题 For an array of integers, a surpasser of an integer element is an element on its right hand side that is larger than it. For example, {10,3,4,5,2} , the surpassers of 3 is 4 and 5 , and 10 doesn't have any surpasser. So the Max Number of Surpassers problem is Given an array of integers Out put the max number of surpassers Basically, we need to get the number of surpassers of every element and finally output the max of them. For example, The max number of surpassers for {10,3,4,5,2} is 2 as 3

Which search is faster, binary search or using prefix tree?

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Suppose I have a list of strings and a prefix tree of those strings, and I would like to locate a string given a key, which one is more faster? binary search or prefix tree search? Why and what's the time complexity? Thanks! Both techniques have their advantages, and their drawbacks: Suffix tree Advantages: O(N) building complexity O(M) search of a pattern of length M They allow online construction Drawbacks: Space inefficient Really complex construction algorithms Binary search (with suffix array) Advantages: You can sort the string array in O(N) time Space efficient (five times less memory

Binary Search and Hashtable Search

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I wanted to find out the trade off point between a Dictionary lookup and a binary search lookup of an array. I was expecting constant time lookups for the Dictionary, and logarithmic time lookups for the binary search depending on the size of the collection, with the binary search performing better for smaller sized collections. However, I was surprised when I saw the following results: I was surprised at: 1. Binary search is growing logarithmically at first, and then grows much faster. 2. Hash is pretty consistent at first, but then also starts growing slowly. 3. Binary search is never better