HDU 3763 CD

  • 2018-08-16
  • 28
  • 0

Description:

Jack and Jill have decided to sell some of their Compact Discs, while they still have some value. They have decided to sell one of each of the CD titles that they both own. How many CDs can Jack and Jill sell?

Neither Jack nor Jill owns more than one copy of each CD.

Input:

The input consists of a sequence of test cases. The first line of each test case contains two non-negative integers N and M, each at most one million, specifying the number of CDs owned by Jack and by Jill, respectively. This line is followed by N lines listing the catalog numbers of the CDs owned by Jack in increasing order, and M more lines listing the catalog numbers of the CDs owned by Jill in increasing order. Each catalog number is a positive integer no greater than one billion. The input is terminated by a line containing two zeros. This last line is not a test case and should not be processed.

Output:

For each test case, output a line containing one integer, the number of CDs that Jack and Jill both own.

Sample Input:

3 3
1
2
3
1
2
4
0 0

Sample Output:

2

题目链接

这道题目有长达6s的时间限制,所以可以开一个“one million”的数组直接存储后暴力查找,题目数据也很水,开个”one million”的标记数组也可以过,但是解这道题更正确的姿势是二分查找,存储Jack的数,对每个Jill的数相当于一个Jack是否有这个数的询问,通过二分查找判断即可,这里也可以用STL的lower_bound。

AC代码:

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