I know the naive method. It's very straight. Just maintain an index array which records the
index of the books. whenever one book is removed then update all elements in the index array after its index. It runs O (M N). I'd like to know is there any efficent data structure to speedup it? Thanks. On Sep 5, 10:14 am, Ray <[EMAIL PROTECTED]> wrote: > He has lost many books, since many of his friends borrow his books and > never bother to return them. He does not want to lose any more books > and has decided to keep a record of all books that he lends to his > friends. To make the task of borrowing a book a little difficult, he > has given the following instructions to his friends: when they borrow > a book, they must record in a register its position from the left > among the books currently on the shelf. > > Suppose there are 5 books in the library and they are arranged as > follows: > > 26 1 42 15 3 > If someone walks in and borrows the book 42, then he will record 3 in > the register because this book is the third from the left on the > shelf. Now the shelf looks like this: > > 26 1 15 3 > If the next person borrow the book 3, he writes down 4 in the register > since this is currently the fourth book from the left on the shelf, > and so on. > > Indraneel knows the initial arrangement of the books in his library at > the time that he introduced the register system. After a while he > examines his register and would like to know which books have been > borrowed. Your task is to write a program to help Indraneel solve this > problem. > > Input format > > The first line of the input contains a single integer M indicating the > number of books in Indraneel's library. The next line contains M > distinct positive integers describing the sequence in which the books > are arranged on the library shelf. The third line of input contains a > single integer N indicating the number of entries in the register. > This, in turn, is followed by N lines (lines 4 to N+3), each > containing one positive integer. The integer on line 3+i indicates the > position from left of the book ith book borrowed. (You may assume that > the number on line 3+i is at most M-i+1.) > > Output format > > N lines with one positive integer on each line. The number on line i > is the book borrowed by the ith borrower. > > Test Data: > > You may assume that 1 ≤ M ≤ 1000000 and 1 ≤ N ≤ 4000. > > Example: > > Here is the sample input and output corresponding to the example > discussed above. > > Sample Input > > 5 > 26 1 42 15 3 > 2 > 3 > 4 > Sample Output > > 42 > 3 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algogeeks@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/algogeeks -~----------~----~----~----~------~----~------~--~---
