数组中的二进制搜索 [英] Binary Search in Array

问题描述

我将如何实现只用一个数组的二进制搜索？

How would I implement a binary search using just an array?

推荐答案

请确保您的数组排序，因为这是一个二进制搜索的症结所在。

Ensure that your array is sorted since this is the crux of a binary search.

任何索引/随机存取的数据结构可以是二进制搜索。所以，当你说用只是一个数组，我会说阵列是一个二进制搜索采用的最基本/常见的数据结构。

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.

您可以做到这一点递归（容易）或反复。时间二进制搜索的复杂度为O（日志N），这是比检查在O（N）的每个元素的线性搜索快得多。以下是维基百科的一些例子：二进制搜索算法：

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 checking each element at O(N). Here are some examples from Wikipedia: Binary Search Algorithm:

递归：

BinarySearch(A[0..N-1], value, low, high) {  
    if (high < low)  
        return -1 // not found  
    mid = low + ((high - low) / 2) 
    if (A[mid] > value)  
        return BinarySearch(A, value, low, mid-1)  
    else if (A[mid] < value)  
        return BinarySearch(A, value, mid+1, high)  
    else
       return mid // found
    }

迭代：

  BinarySearch(A[0..N-1], value) {
   low = 0
   high = N - 1
   while (low <= high) {
       mid = low + ((high - low) / 2)
       if (A[mid] > value)
           high = mid - 1
       else if (A[mid] < value)
           low = mid + 1
       else
           return mid // found
   }
   return -1 // not found
}

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