快读

getchar_unlocked()快读

getchar_unlocked() 的速度比 fread() 略逊一筹，但是有代码短小精悍的优点，可以在比赛中直接使用

Code:

namespace getchar_unlocked_fastread {
	const void read(int &x)
	{
		x = 0; int f = 1; char c = getchar_unlocked();
		while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar_unlocked();}
		while(c >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c ^ 48), c = getchar_unlocked(); 
             //(x << 3) + (x << 1) 相当于x * 10
		x *= f;
	}
}using getchar_unlocked_fastread::read;

fread()快读

fread()快读是目前最快的快读，但是有读入的缓存区，占内存

Code:

namespace fread_fastread {
    const int S = 1 << 20;
    char buf[S], *H, *T;
	char getchar()
	{
		if(H == T) T = (H = buf) + fread(buf, 1, S, stdin);
		return (H == T) ? EOF : *H ++ ;
	}
	
	const void read(int &x)
	{
		x = 0; int f = 1; char c = getchar();
		while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
		while(c >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
		x *= f;
	}
} using fread_fastread::read;