【总结】初等数论总结

https://blog.youkuaiyun.com/CYCKCN/article/details/68165147

费马平方和定理：奇质数能表示为两个完全平方数之和，当且仅当它是4k+1型。换句话说能表示为两个完全平方数之和的数的4k+3因子必定有偶数次。https://blog.youkuaiyun.com/bigbigship/article/details/27234325

1.线性求逆元

证明在http://blog.miskcoo.com/2014/09/linear-find-all-invert

inv[i] = -(p / i) * inv[p % i];

2.线性筛法

inline void solve(int n) {
  check[0] = 1, check[1] = 1;
  for (int i = 2; i <= n; ++i) {
    if (!check[i]) prim[++tot] = i;
    for (int j = 1; j <= tot && i * prim[j] <= n; ++j) {
      check[i * prim[j]] = 1;
      if (i % prim[j] == 0) break;
    }
  }
}

3.求出所有因子

for (int i = 1; i * i <= x; ++i)
  if (x % i == 0) {
    ans[++cnt] = i;
    if (i * i != x) ans[++cnt] = x / i;
}

2.多项式乘法的快速傅里叶变换和快速数论变换，生成函数

http://blog.miskcoo.com/2015/04/polynomial-multiplication-and-fast-fourier-transform

 

 

3.