for2)You are very far from understanding the problem.

來源: 2011-03-21 10:37:44 [舊帖] [給我悄悄話] 本文已被閱讀:

Only permutation, there is a byjection.

for 1) I thnk I am right,first step is intergral repreresentation.Planting in gap correspondto circling a letter, Pting crossing a line,...two letters.If you don't think so,we can try, you first, I second, I'll win.