摘要：
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of 阅读全文
摘要：
Given an array of integers, find how many unique pairs in the array such that their sum is equal to a specific target number. Please return the number 阅读全文
摘要：
Given an array of integers, find how many pairs in the array such that their sum is less than or equal to a specific target number. Please return the 阅读全文