1 . 优化 ```cpp #pragma GCC optimize("O3,unroll-loops") #pragma GCCtarget("avx2,bmi,bmi2,lzcnt,popcnt") ``` 快读快写 ```cpp long long read() { long long x=0,f=1;char ch=getchar(); while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();} while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();} return x*f; } void print(int x) { if(x<0){putchar('-');x=-x;} if(x>9) print(x/10); putchar(x%10+'0'); } ``` 2 .随机化哈希可用`mt19937_64` ```cpp mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); ll g...