# SkyWT

Fighting 2019!

Linux 下有些时候我们运行一个进程需要一直挂着（这就是 VPS 的意义啊……），这时候需要把前台进程放到后台去。一般可以用 screen，但是如果这种后台进程挂多了，每个都开一个 session 会很不方便。前几天配置 aria2 的时候看到一个神奇的操作：可以配置成一个 service，直接 service aria2c start/stop/restart 就可以了！

## Description

Ivan wants to make a necklace as a present to his beloved girl. A necklace is a cyclic sequence of beads of different colors. Ivan says that necklace is beautiful relative to the cut point between two adjacent beads, if the chain of beads remaining after this cut is a palindrome (reads the same forward and backward).

## Description

In mathematical terms, the sequence F_n of Fibonacci numbers is defined by the recurrence relation

F_1 = 1; F_2 = 1; F_n = F_{n - 1} + F_{n - 2} (n > 2)

DZY loves Fibonacci numbers very much. Today DZY gives you an array consisting of n integers: a_1, a_2, \dots, a_n. Moreover, there are m queries, each query has one of the two types:

The cool breeze blows gently, the flowing water ripples steadily.

"Flowing and passing like this, the water isn't gone ultimately; Waxing and waning like that, the moon doesn't shrink or grow eventually."
"Everything is transient in a way and perennial in another."

Kanno doesn't seem to make much sense out of Mino's isolated words, but maybe it's time that they enjoy the gentle breeze and the night sky — the inexhaustible gifts from nature.

Gazing into the sky of stars, Kanno indulges in a night's tranquil dreams.

## 引言

Bitset 是一种利用对布尔数组压位存储的方法，达到优化时间常数、空间常数的目的的黑科技。利用 Bitset，可以方便地对布尔数组进行按位逻辑运算，优化 32 或 64 的常数。在某些素质极差的卡常题中运用会有奇效。

## Description

1. 堆排序、快速排序、希尔排序、直接选择排序不是稳定的排序算法；
2. 基数排序、冒泡排序、直接插入排序、折半插入排序、归并排序是稳定的排序算法。

• 默认
• 护眼
• 夜晚
• Serif
• Sans