OJ Board

Dear all,
Does ACM have any problem that is given a pre-order & post-order.
Then asking how many possible tree can match this kind of order ?

Hi ,
I was wandering can some one give the math proof of 711's reduce method..
I have saw someone 's code write like the follows :
for (i=0;i<6;++i)
if (input >6)
input = 6 + ((input -6)%2);

And he say that the proof is because any two pair of the number's gcd is at most times 6..
etc : (5,6 ...

Hello all,

Have you ever write some problem that it is NP-Complete
(Like 307 )
Or some problem that is NP , but in the problem's special restrcution..
It becomes non-NP..
(Like 10000)
Please tell me on board or via private message , thanks !!
I really wanna practice problem like these.
(I have try ...

Is there some problem that use algorithm MST ?
Need some pracetice ^^

And also want to practice some problem that is
(Max-Flow min-cost), (Divide-Conquer) ,
(IDA* and A*)
too ^^"..

Thanks,
Peter