Problem Show that there exists two non-negative functions f and g (i.e. f, g : N → R*) such that f≠O(g), f≠θ (g), and f≠Ω(g). Solution sin、cos函數 題目要求非負整數，所以取絕對值 兩函數不會在大於某個N之後恆大(小)於另一方 滿足題目要求 f(n) = |sin(n)| g(n) = |cos(n)|