Source: https://leetcode.com/problems/intersection-of-two-arrays-ii/

Given two arrays, write a function to compute their intersection.

Read MoreSource: https://leetcode.com/problems/intersection-of-two-arrays-ii/

Given two arrays, write a function to compute their intersection.

Read MoreSource: https://leetcode.com/problems/intersection-of-two-arrays/

Given two arrays, write a function to compute their intersection.

Read MoreSource: https://leetcode.com/problems/top-k-frequent-elements/

Given a non-empty array of integers, return the ** k** most frequent elements.

Source: 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] = nums[j]**and the **absolute** difference between *i* and *j* is at most *k*.

Source：https://leetcode.com/problems/happy-number/

Write an algorithm to determine if a number is “happy”.

Read MoreSource: https://leetcode.com/problems/single-number/

Given a **non-empty** array of integers, every element appears *twice* except for one. Find that single one.