Leetcode - 532. K-diff Pairs in an Array

Example 1:

Input:[3, 1, 4, 1, 5], k = 2

Output:2

Explanation:There are two 2-diff pairs in the array, (1, 3) and (3, 5).

Although we have two 1s in the input, we should only return the number ofuniquepairs.

Example 2:

Input:[1, 2, 3, 4, 5], k = 1

Output:4

Explanation:There are four 1-diff pairs in the array, (1, 2), (2, 3), (3, 4) and (4, 5).

Example 3:

Input:[1, 3, 1, 5, 4], k = 0

Output:1

Explanation:There is one 0-diff pair in the array, (1, 1).

question

解法：

hashtable

首先将 list 转换成哈希表，这样做可以是搜索为O(1), which is nice

对 nums 中每个数字进行搜索

如果 num + diff 在 hashtable里面说明存在一个条件的数字存在 count+=1

......  num - diff  ........................ count+=1

内存消耗：

O(n) + O(m)

时间消耗：

O(n)

代码： 代码存在一些处理edge case的：