《Cracking the Coding Interview》——第11章：排序和搜索——题目4

2014-03-21 21:28

题目：给定一个20GB大小的文本文件，每一行都是一个字符串。请设计方法将这个文件里的字符串排序。

解法：请看下面的注释。

代码：

 1 // 11.4 Given a file of 20GB containing strings, one word each line. How would you sort them all?

 2 // Answer:

 3 //    1. Split them into 200M pieces.

 4 //    2. For each pieces, use comparison sort or hashing to sort it in memory.

 5 //    3. After sorting each pieces, output it back to a file.

 6 //    4. Merge the 100 pieces with multiprocess, speed up the merging with a heap or something.

 7 //    5. You can't load all full pieces into memory, load one small piece of a piece at a time.

 8 //    6. When this small piece is merged into final result, load the next small piece.

 9 //    7. I suppose it's completely acceptable for a relatively good PC to afford such IO and computation.

10 int main()

11 {

12     return 0;

13 }