# 清风的技术小屋

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## 问题描述

Given an array of integers and an integer k, you need to find the number of unique k-diff pairs in the array. Here a k-diff pair is defined as an integer pair (i, j), where i and j are both numbers in the array and their absolute difference is k.

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 of unique pairs.

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).

Note:

1. The pairs (i, j) and (j, i) count as the same pair.
2. The length of the array won't exceed 10,000.
3. All the integers in the given input belong to the range: [-1e7, 1e7].

## 解决方案

• 如果 $$a = b-k$$ 在第一个容器中，保存 $$\min(a, b) = b - k$$ 到第二个容器中
• 如果 $$a = b + k$$ 在第一个容器中，保存 $$\min(a, b) = b$$ 到第二个容器中
• 如果上述条件都不满足，说明没有找到相应的数字对，将元素 $$b$$ 放入到第一个容器中