快速读入

整理一下快读的板子，方便自己复制

getchar版：

int read()
{
    int x = 0, f = 1;
    char c = getchar();
    while (!isdigit(c))
    {
        if (c == '-')
            f = -1;
        c = getchar();
    }
    while (isdigit(c))
    {
        x = (x << 3) + (x << 1) + (c ^ 48);
        c = getchar();
    }
    return x * f;
}

fread版：

宏定义版：

#define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 21, stdin), p1 == p2) ? EOF : *p1++)
char buf[1 << 21], *p1 = buf, *p2 = buf;
int read()
{
    int x = 0, f = 1;
    char c = gc();
    while (!isdigit(c))
    {
        if (c == '-')
            f = -1;
        c = gc();
    }
    while (isdigit(c))
    {
        x = (x << 3) + (x << 1) + (c ^ 48);
        c = gc();
    }
    return x * f;
}

函数版：

char buf[1 << 21], *p1 = buf, *p2 = buf;
char gc()
{
    if (p1 != p2)
        return *p1++;
    p1 = buf;
    p2 = p1 + fread(buf, 1, 1 << 21, stdin);
    return p1 == p2 ? EOF : *p1++;
}
int read()
{
    int x = 0, f = 1;
    char c = gc();
    while (!isdigit(c))
    {
        if (c == '-')
            f = -1;
        c = gc();
    }
    while (isdigit(c))
    {
        x = (x << 3) + (x << 1) + (c ^ 48);
        c = gc();
    }
    return x * f;
}