Prime Path

The ministers of the cabinet were quite upset by the message from the Chief of Security stating that they would all have to change the four-digit room numbers on their offices.
— It is a matter of security to change such things every now and then, to keep the enemy in the dark.
— But look, I have chosen my number $1033$ for good reasons. I am the Prime minister, you know!
— I know, so therefore your new number $8179$ is also a prime. You will just have to paste four new digits over the four old ones on your office door.
— No, it’s not that simple. Suppose that I change the first digit to an $8$, then the number will read 8033 which is not a prime!
— I see, being the prime minister you cannot stand having a non-prime number on your door even for a few seconds.
— Correct! So I must invent a scheme for going from $1033$ to $8179$ by a path of prime numbers where only one digit is changed from one prime to the next prime.

第六章——字符串操作

• 字符串以单（双）引号开始，单（双）引号结束

• 在字符串开始的引号之前加上r，可以将字符串称为原始字符串，打印出字符串中所有的\之类的转义字符

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第五章——字典和结构化数据

字典

• 字典的索引被称为键，键及其关联的值称为键-值。字典输入的时候要带花括号{}，在使用的时候和列表一样使用中括号[]

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from numpy import*导入numpy模块

random.rand()用来生成一个随机数组

第三章——函数

• None表示没有值，是NoneType数据类型的唯一值。print的返回值就是None

• print()函数有可选的变元end和sep，分别指定在参数末尾打印什么，在参数之间打印什么来隔开它们

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第一章——Python基础

vim的配置文件

快速幂相关

快速幂（二分幂）

时间复杂度：$O(logn)$

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int Pow(int a,int b,int c)
{
	int res=1;
	while(b>0)
	{
		if(b&1) res=res*a%c;
		a=a*a%c;
		b>>=1;
	}
	return res;
}//复杂度O(logn)

DP

01背包（每种物品只有一个）

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//n 物品数量，v 背包容量 
//size 单个物品体积，value 单个物品价值
void bag01()
{
    for(int i=0;i<n;i++)
    for(int j=v;j>=size[i];j--)
    {
        dp[j]=max(dp[j],dp[j-size[i]]+value[i]);
    }
    cout<<dp[v]<<endl;
}