1051 Wooden Sticks

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12443    Accepted Submission(s): 5167

Problem Description

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 (4,9), (5,2), (2,1), (3,5), and (1,4), then the minimum setup time should be 2 minutes since there is a sequence of pairs (1,4), (3,5), (4,9), (2,1), (5,2).

 

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 n 2 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.

 

Output

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

 

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

 

Sample Output

2

1

3

Source

Asia 2001, Taejon (South Korea)

 #include<iostream>
 #include<math.h>
 #include<stdio.h>
 #include<stdlib.h>
 #include<string.h>
 #include<algorithm>
 using namespace std;
 struct ln{
     int x;
     int y;
     int z;
 }a[];
 bool cmp(const ln a,const ln b)
 {
     if(a.y==b.y)
     return a.x<b.x;
     else
     return a.y<b.y;
 }
 int main()
 {
     //freopen("in.txt","r",stdin);
     int t;
     scanf("%d",&t);
     while(t--)
     {
         memset(a,,sizeof(a));
         int n;
         scanf("%d",&n);
         for(int i=;i<n;i++)
         {
             scanf("%d%d",&a[i].x,&a[i].y);
             a[i].z=;
         }
         sort(a,a+n,cmp);
         int count=,length;
         for(int i=;i<n;i++)
         {
             if(!a[i].z)
             {
                 count++;
                 length=a[i].x;
                 for(int j=i+;j<n;j++)
                 {
                     if(!a[j].z)
                     {
                        if(a[j].x>=length)
                        {
                            a[j].z=;
                            length=a[j].x;
                        }
                     }

                 }
             }

         }
         printf("%d\n",count);
     }
     return ;
 }