binary-search

java Arrays.binarySearch fails to find target

由 百般思念 提交于 2019-11-26 17:24:17
问题 String[] sortedArray = new String[]{"Quality", "Name", "Testing", "Package"}; // Search for the word "cat" int index = Arrays.binarySearch(sortedArray, "Quality"); I always get -3 . Problem is in "Name" . Why I can not have "Name" in my array? Any idea? 回答1: In order to use binarySearch , you will need to sort the array yourself first: String[] sortedArray = new String[]{"Quality", "Name", "Testing", "Package"}; java.util.Arrays.sort(sortedArray); int index = Arrays.binarySearch(sortedArray,

Binary search algorithm in python

由 冷暖自知 提交于 2019-11-26 13:53:11
问题 I am trying to implement the binary search in python and have written it as follows. However, I can't make it stop whenever needle_element is larger than the largest element in the array. Can you help? Thanks. def binary_search(array, needle_element): mid = (len(array)) / 2 if not len(array): raise "Error" if needle_element == array[mid]: return mid elif needle_element > array[mid]: return mid + binary_search(array[mid:],needle_element) elif needle_element < array[mid]: return binary_search

How to perform a binary search on IList<T>?

由 允我心安 提交于 2019-11-26 12:27:22
问题 Simple question - given an IList<T> how do you perform a binary search without writing the method yourself and without copying the data to a type with build-in binary search support. My current status is the following. List<T>.BinarySearch() is not a member of IList<T> There is no equivalent of the ArrayList.Adapter() method for List<T> IList<T> does not inherit from IList , hence using ArrayList.Adapter() is not possible I tend to believe that is not possible with build-in methods, but I

How to find the kth smallest element in the union of two sorted arrays?

由 …衆ロ難τιáo~ 提交于 2019-11-26 10:59:25
This is a homework question. They say it takes O(logN + logM) where N and M are the arrays lengths. Let's name the arrays a and b . Obviously we can ignore all a[i] and b[i] where i > k. First let's compare a[k/2] and b[k/2] . Let b[k/2] > a[k/2] . Therefore we can discard also all b[i] , where i > k/2. Now we have all a[i] , where i < k and all b[i] , where i < k/2 to find the answer. What is the next step? You've got it, just keep going! And be careful with the indexes... To simplify a bit I'll assume that N and M are > k, so the complexity here is O(log k), which is O(log N + log M). Pseudo

how to calculate binary search complexity

由 你离开我真会死。 提交于 2019-11-26 08:39:46
问题 I heard somebody say that since binary search halves the input required to search hence it is log(n) algorithm. Since I am not from a mathematics background I am not able to relate to it. Can somebody explain it in a little more detail? does it have to do something with the logarithmic series? 回答1: Here a more mathematical way of seeing it, though not really complicated. IMO much clearer as informal ones: The question is, how many times can you divide N by 2 until you have 1? This is

How can I simplify this working Binary Search code in C?

由 空扰寡人 提交于 2019-11-26 08:38:25
问题 Hey guys started programming in C few weeks ago learning about algothiritms, just wondering how would you make my code more simple its just a binary search function. But the only thing is you must keep the arguments the same, thanks in advance. bool search(int value, int values[], int n) { int min = values[0]; int max = values[n-1]; int average = (min + max) / 2; if(average == value) { return true; } while (average > value) { max = average - 1; average = (min + max) / 2; } while (average <

Binary Search in Array

由 一世执手 提交于 2019-11-26 06:39:56
问题 How would I implement a binary search using just an array? 回答1: Ensure that your array is sorted since this is the crux of a binary search. Any indexed/random-access data structure can be binary searched. So when you say using "just an array", I would say arrays are the most basic/common data structure that a binary search is employed on. You can do it recursively (easiest) or iteratively. Time complexity of a binary search is O(log N) which is considerably faster than a linear search of

Binary Search in Javascript

由 丶灬走出姿态 提交于 2019-11-26 05:29:52
问题 I\'m trying to implement a binary search algorithm in JavaScript. Things seem okay, but my return statements appear to be returning undefined? Can anybody tell what\'s wrong here? Fiddle: http://jsfiddle.net/2mBdL/ Thanks. var a = [ 1, 2, 4, 6, 1, 100, 0, 10000, 3 ]; a.sort(function (a, b) { return a - b; }); console.log(\'a,\', a); function binarySearch(arr, i) { var mid = Math.floor(arr.length / 2); console.log(arr[mid], i); if (arr[mid] === i) { console.log(\'match\', arr[mid], i); return

Where can I get a “useful” C++ binary search algorithm?

由 元气小坏坏 提交于 2019-11-26 05:22:42
问题 I need a binary search algorithm that is compatible with the C++ STL containers, something like std::binary_search in the standard library\'s <algorithm> header, but I need it to return the iterator that points at the result, not a simple boolean telling me if the element exists. (On a side note, what the hell was the standard committee thinking when they defined the API for binary_search?!) My main concern here is that I need the speed of a binary search, so although I can find the data with

What is the performance impact of non-unique indexes in pandas?

由 元气小坏坏 提交于 2019-11-26 04:47:15
问题 From the pandas documentation, I\'ve gathered that unique-valued indices make certain operations efficient, and that non-unique indices are occasionally tolerated. From the outside, it doesn\'t look like non-unique indices are taken advantage of in any way. For example, the following ix query is slow enough that it seems to be scanning the entire dataframe In [23]: import numpy as np In [24]: import pandas as pd In [25]: x = np.random.randint(0, 10**7, 10**7) In [26]: df1 = pd.DataFrame({\'x\
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