James Pan

原题网址：https://leetcode.com/problems/repeated-dna-sequences/ All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is someti

原题网址：https://leetcode.com/problems/longest-consecutive-sequence/ Given an unsorted array of integers, find the length of the longest consecutive elements sequence. For example, Given [100, 4,

原题网址：https://leetcode.com/problems/happy-number/ Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive

原题网址：https://leetcode.com/problems/contains-duplicate/ Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in

原题网址：https://leetcode.com/problems/contains-duplicate-ii/ Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = num

原题网址：https://leetcode.com/problems/permutations-ii/ Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the followi