摘要：
A sequence of numbers is called arithmetic if it consists of at least two elements, and the difference between every two consecutive elements is the s 阅读全文
摘要：
Given a 0-indexed integer array nums of size n and two integers lower and upper, return the number of fair pairs. A pair (i, j) is fair if: 0 <= i < j 阅读全文
摘要：
Given a 0-indexed integer array nums of length n and an integer target, return the number of pairs (i, j) where 0 <= i < j < n and nums[i] + nums[j] < 阅读全文