Build an aarch64 UEFI image for QEMU

This artile is used for build a new arm guest machine for qemu. I start from a netinstaller, create UEFI flash, set qemu command line, then install it.

How to build a kernel package for debian

This is a manual to compile a new kernel package for Debian.  It's all based on apt-get command, install necessary application, get source code and set configuration file, then get make and install.

Never be negative

Print right view of binary tree

Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

For example:
Given the following binary tree,

   1            <---
 /   \
2     3         <---
 \     \
  5     4       <---

You should return [1, 3, 4].

Credits:
Special thanks to @amrsaqr for adding this problem and creating all test cases.

Number times

Single Number I, all twice except one single

Single Number II All numbers occurs triple times except one once

Single Number II All numbers occurs triple times except one twice

Single Number III  all twice numbers, except two single Number