MSTICK - Wooden Sticks

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There is a pile of  n  wooden sticks. The length and weight of each stick
are known in advance. The sticks are to be processed by a woodworking machine
in one by one fashion. It needs some time, called setup time, for the  machine
to  prepare  processing  a  stick.  The  setup  times  are  associated  with
cleaning  operations  and changing tools and shapes in the machine. The setup
times of the woodworking machine are given as follows: 
 
(a) The setup time for the first wooden stick is 1 minute. 
(b) Right after processing a stick of length  l  and weight  w , the machine will
need no setup time for a stick of length  l'  and weight  w'  if  l ≤ l' and  w ≤ w'. 
Otherwise, it will need 1 minute for setup. 
 
You are to find the minimum setup time to process a given pile of  n  wooden sticks. 
For example, if you have five sticks whose pairs of length and weight are  
( 9 , 4 ) , ( 2 , 5 ) , ( 1 , 2 ) , ( 5 , 3 ) , and ( 4 , 1 ) , then the minimum
setup time should be 2 minutes since there is a sequence of pairs ( 4 , 1 ) , 
( 5 , 3 ) , ( 9 , 4 ) , ( 1 , 2 ) , ( 2 , 5 ) .

Input

The input consists of T test cases. The number of test cases (T) is given 
in the first line of the input file. Each test case consists of two lines:
 The first line has an integer n , 1 <= n <= 5000 , that represents the number 
of wooden sticks in the test case, and the second line contains 2n positive
integers l1 , w1 , l2 , w2 ,..., ln , wn , each of magnitude at most 10000 ,
where li and wi are the length and weight of the i th wooden stick, respectively.
The 2n integers are delimited by one or more spaces.

SAMPLE INPUT
3 
5 
4 9 5 2 2 1 3 5 1 4 
3 
2 2 1 1 2 2 
3 
1 3 2 2 3 1 

Output

 
The output should contain the minimum setup time in minutes, one per line. 

SAMPLE OUTPUT
2
1
3

hide comments
bristy: 2016-02-10 10:02:39

Extra challenge try cases if l1 < l2 and w1<=w2, l1 <= l2 and w1<w2. l1 < l2 and w1<w2 (same as MDOLLS).

anando_du: 2015-03-07 14:15:56

if u have solved MDOLLS then i think u don't need to code it again :P but be careful about sorting and remember l1<=l2 && w1<=w2 .

vishal: 2014-09-27 12:45:03

plz can any one give me some test cases

46
56
78
86
98
my code is giving 2 is it right
10
10
20
30
40
mine is 1
are they right..?

Harits Elfahmi: 2010-07-13 13:06:23

Can anyone give more testcase(s)?
mine worked for the sample, but get wrong answer...

~!(*(@*!@^&: 2009-03-10 03:01:12

Similar problem is MDOLLS.


Added by:~!(*(@*!@^&
Date:2009-02-23
Time limit:0.328s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO NODEJS PERL6 VB.NET
Resource:Taejon 2002