PDD newp(now.x + ((long double)(rand() << 1) - RAND_MAX) * T, now.y + ((long double)(rand() << 1) - RAND_MAX) * T);

上面这种写法会全 WA。

PDD newp(now.x + (long double)((rand() << 1) - RAND_MAX) * T, now.y + (long double)((rand() << 1) - RAND_MAX) * T);

而这种写法就 AC 了。

求问大佬这是为什么？