学习笔记

快速幂模板
例题

long long qpow(long long a,long long b)
{
    long long res = 1 % mod;
    while(b)
    {
        if(b & 1) res = (res * a) % mod;
        a = a * a % mod;
        b >>= 1; 
    }
    return res;
}

快速乘模板

[例题](https://www.acwing.com/problem/content/92/) 
```c++
long long qmul(long long a,long long b)
{
    long long res = 0;
    while(b)
    {
        if(b & 1) res = (res + a) % mod;
        a = a * 2 % mod;
        b >>= 1; 
    }
    return res;
}