如何执行上的NSArray二进制搜索？ [英] How to perform binary search on NSArray?

问题描述

什么是做一个二进制搜索最简单的方法是（已经）进行分类的NSArray ？

What is the simplest way to do a binary search on an (already) sorted NSArray?

我已经发现迄今一些可能的方式包括：

Some potential ways I have spotted so far include:

1. 使用 CFArrayBSearchValues​​ 的（自提<一个href="https://developer.apple.com/library/mac/#documentation/CoreFOundation/Reference/CFArrayRef/Reference/reference.html">here) - 将这项工作在一个的NSArray

2. 方法 indexOfObject：inSortedRange：选项：usingComparator： 的NSArray 的假设数组排序，需要一个选择采用类型的参数 NSBinarySearchingOptions - 这是否意味着它执行的二进制搜索？该<一href="https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/NSArray.html">docs只是说：

1. The use of CFArrayBSearchValues (mentioned here) - would this work on an NSArray?

2. The method indexOfObject:inSortedRange:options:usingComparator: of NSArray assumes the array is sorted and takes an opts param of type NSBinarySearchingOptions - does this mean it performs a binary search? The docs just say:

通过使用给定的NSComparator块阵列中的元素进行比较返回对象的索引，在指定的范围内，

Returns the index, within a specified range, of an object compared with elements in the array using a given NSComparator block.

写我自己的二进制搜索法（沿这东西线）。

Write my own binary search method (something along the lines of this).

我要补充一点，我编程的iOS 4.3 +

I should add that I am programming for iOS 4.3+

在此先感谢。

推荐答案

1和2两个工作。 ＃2可能是更容易;它肯定没有任何意义的方法做任何事情比二进制搜索（如果范围是具有一定规模的，说了）等。你可以验证一个大阵，它只做少量的比较。

1 and 2 will both work. #2 is probably easier; it certainly doesn't make sense for that method to do anything other than a binary search (if the range is above a certain size, say). You could verify on a large array that it only does a small number of comparisons.

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