167. Two Sum II — Input array is sorted
Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.
283. Move Zeroes
Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.
nums
0
Example:
Input: [0,1,0,3,12]Output: [1,3,12,0,0]
[0,1,0,3,12]
[1,3,12,0,0]
102. Binary Tree Level Order Traversal
Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).
For example:Given binary tree [3,9,20,null,null,15,7],
[3,9,20,null,null,15,7]
Count and Say
The count-and-say sequence is a sequence of digit strings defined by the recursive formula:
countAndSay(1) = "1"
countAndSay(n)
countAndSay(n-1)
Single Number
Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.
Follow up: Could you implement a solution with a linear runtime complexity and without using extra memory?
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 the array, and it should return false if every element is distinct.