03/21/2010 SUN Sunny
“Hi, boys and girls ,today we will learn the “Deference” .”
“What is the “Deference”? Is that difficult? ”
“Boys , don’t worry, and you will know it immediately.”
“f(x) is an function, and x is an integer. Δf( x ) = f (x + 1 ) – f( x ) ”
“In general, Δ(n+1)f( x ) = Δ(n)f( x+1 ) - Δ(n)f( x )”
“In particular, Δ(0)f( x ) = f( x ),Δ(1)f( x ) = Δf (x )”
“Do you understand?”
“No!!!!!!!!!!!!”
“Does anyone understand?”
“Only you our teacher!”
“How dare you be so ironic. Since you all have learnt the Factorial. I will give you a problem of factorial and difference. Anyone who can’t solve it will be severely punished”
“ The problem is:
Given a nonnegative integer array {a[n]} , and each of its elements a[i] (1<=i<=n)is also known.
f(x)=∏{1<=i<=n}(x+a[i])
Your task is to calculate Δ(k)f(0)/k! ”
Damn it,really bad mood. Well, I'd better go to sleep now.