binary-search

问题 What is the difference between binary search and binary search tree? Are they the same? Reading the internet it seems the second is only for trees (up to 2 children nodes) and binary search doesn't follow this rule. I didn't quite get it. 回答1: Binary Search Trees A node in a binary tree is a data structure that has an element, and a reference to two other binary trees, typically called the left and right subtrees. I.e., a node presents an interface like this: Node: element (an element of some

问题 I have string array [1, 2, 3] and i search for all of those numbers using Arrays.binarySearch, it find 1 and 2, but with 3 it returns -1. any idea why it works that way? what is better alternative to always working search in array/collection? 回答1: An array must be sorted. String []ar={"1","2","3"}; System.out.println(java.util.Arrays.binarySearch(ar,"3")); 来源： https://stackoverflow.com/questions/1356621/arrays-binarysearch-doesnt-work-like-it-should

问题 What is the best way to search in a circular array? Example 1 array : 45 67 44 11 49 4 56 12 39 90 circular array 11, 49, 4, 56, 12, 39, 90, 45, 67 Is Binary search the right approach to start with? 回答1: Binary search is only useful if the array is sorted. You didn't provide much info about the problem domain but one approach would be to use a set (or hash table). For every number you put in the array, also insert it in the set. Lookups in a set (or hash table) happen in constant time, so

问题 I have this Player class which implements the Comparable interface. Then I have an ArrayList of Player s. I'm trying to use binarySearch() on the list of Player s to find one Player , but Java is giving me a " cannot find symbol: method binarySearch(java.util.ArrayList< Player>,Player) ". This the Player class: class Player implements Comparable { private String username; private String password; Statistics stats; //Constructor, creates a new Player with a supplied username Player(String name

问题 I'm having trouble combining these two algorithms together. I've been asked to modify Binary Search to return the index that an element should be inserted into an array. I've been then asked to implement a Binary Insertion Sort that uses my Binary Search to sort an array of randomly generated ints . My Binary Search works the way it's supposed to, returning the correct index whenever I test it alone. I wrote out Binary Insertion Sort to get a feel for how it works, and got that to work as

问题 I want to find a sequence of items in a sorted array of values. I know that with numpy I can do: l = np.searchsorted(values, items) This has the complexity of O(len(items)*log(len(values))). However, my items are also sorted, so I can do it in O(len(items)+len(values)) doing: l = np.zeros(items.size, dtype=np.int32) k, K = 0, len(values) for i in range(len(items)): while k < K and values[k] < items[i]: k += 1 l[i] = k The problem is that this version in pure python is way slower than

问题 I want to find a sequence of items in a sorted array of values. I know that with numpy I can do: l = np.searchsorted(values, items) This has the complexity of O(len(items)*log(len(values))). However, my items are also sorted, so I can do it in O(len(items)+len(values)) doing: l = np.zeros(items.size, dtype=np.int32) k, K = 0, len(values) for i in range(len(items)): while k < K and values[k] < items[i]: k += 1 l[i] = k The problem is that this version in pure python is way slower than

问题 I'm trying to understand how do I modify the binary search for it work for first and last occurrences, surely I can find some code on the web but I'm trying to reach deep understanding, here is some basic non-recursive binary search I found: int BinarySearch(int *array, int number_of_elements, int key) { int low = 0, high = number_of_elements-1, mid; while(low <= high) { mid = (low + high)/2; if(array[mid] < key) { low = mid + 1; } else if(array[mid] == key) { return mid; } else if(array[mid]

问题 Is binary search optimal in worst case? My instructor has said so, but I could not find a book that backs it up. We start with an ordered array, and in worst case(worst case for that algorithm), any algorithm will always take more pairwise comparisons than binary search. Many people said that the question was unclear. Sorry! So the input is any general sorted array. I am looking for a proof which says that any search algorithm will take at least log2(N) comparisons in worst case(worst case

问题 Is binary search optimal in worst case? My instructor has said so, but I could not find a book that backs it up. We start with an ordered array, and in worst case(worst case for that algorithm), any algorithm will always take more pairwise comparisons than binary search. Many people said that the question was unclear. Sorry! So the input is any general sorted array. I am looking for a proof which says that any search algorithm will take at least log2(N) comparisons in worst case(worst case