hdu 6003 Problem Buyer（贪心）

Problem Buyer

Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 195    Accepted Submission(s): 60

Problem Description

TopSetter is an organization that creates problems. They’ve prepared N problems with estimated difficulty score in range [  Ai,Bi ]. TopHoster would like to host a contest consisting of M problems.
The  ith problem should be of difficulty score  Ci. The  ith problem from TopSetter can be used in the contest if and only if its estimated difficulty score range  [Ai,Bi] covers the difficulty score c of its target problem in the contest, i.e.  Ai≤c≤Bi . Hosting a contest with M problems needs tohave M distinct problems which satisfy the required difficulty scores for each problem.
Unfortunately, TopSetter doesn’t provide a service to buy specific problems. You can only request a problem set containing K problems and they will give you K distinct problems from all the N problems, but you don’t know which problems will be given.
As TopSetter is the only problem provider for TopHoster, TopHoster would like to know the least number K of problems they need to buy to make sure they can host a contest.

 

Input

The first line of the input gives the number of test cases, T. T test cases follow. Each test case starts with 2 integers, N and M. Then N lines follow, each line consists of 2 integers representing the difficulty score range of the  ith problem,  AiandBi . The last line of each test case consists of M integers representing the target difficulty scores of the M problems  Ci .

 

Output

For each test case, output one line containing “Case #x: y”, where x is the test case number (starting from 1) and y is the least number of problems which the TopHoster needs to buy.
Output “IMPOSSIBLE!” if it’s impossible.

limits

∙1≤T≤100.
∙1≤N,M≤105.
∙1≤Ai≤Bi≤109.
∙1≤Ci≤109.

 

Sample Input

3 3 1 1 4 2 3 5 6 3 3 2 1 10 3 4 7 9 4 8 3 3 1 2 5 6 8 9 1 5 10

 

Sample Output

Case #1: 2 Case #2: 2 Case #3: IMPOSSIBLE!

读了好久连题目意思都读不懂。。。

真是一道超级难想的贪心题

题意：给出n个区间，m个数，让你任意选k个数，使一定能包含这m个数，一个区间只能包含一个数 求最小的k

解：难就难在 任意 二字 解题思路是 求出一个数的所有满足区间 那么这个区间取一个数即可包含这个数 那么ans=n-size+1

解题报告：http://www.cnblogs.com/xiaochaoqun/p/7243606.html

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