发现如果两个在pre-排序的数组和元素等于某个值 [英] Finding if two elements in a pre-sorted array sum to equal a certain value

问题描述

我工作的一门功课的问题，我有一些困难，创造一个为O（n * LOGN）解决方案。我需要编写一个函数，接受pre排序阵列和一个值来搜索。那么我需要找到如果数组总和的任意两个元素等于该值。

I'm working on a homework problem and I'm having some difficulties creating a O(n*logn) solution. I need to write a function that takes a pre-sorted array and a value to search for. I then need to find if any two elements of the array sum to equal that value.

我需要创建两个O（n）和O（​​N * LOGN）算法这一点。

I need to create both O(n) and O(n*logn) algorithms for this.

在为O​​（n），很容易产生;但是，我有创造的O（N * LOGN）算法，而不在一些无端code实际上并没有解决问题有助于增加困难。如果任何人都可以给我什么，我可能会丢失这将是AP preciated一些指点。

The O(n) was easy to create; however, I am having difficulties creating the O(n*logn) algorithm without adding in some gratuitous code that doesn't actually help in solving the problem. If anyone could give me some pointers on what I might be missing it would be appreciated.

推荐答案

在开始的第一个元素，并依次进入。而，搜索使用二进制搜索第二元件。

Start at the first element, and go sequentially. While that, search for the second element using binary search.

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