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)

 

 1 #include<iostream> 2 #include<math.h> 3 #include<stdio.h> 4 #include<stdlib.h> 5 #include<string.h> 6 #include<algorithm> 7 using namespace std; 8 struct ln{ 9     int x;10     int y;11     int z;12 }a[5009];13 bool cmp(const ln a,const ln b)14 {15     if(a.y==b.y)16     return a.x<b.x;17     else18     return a.y<b.y;19 }20 int main()21 {22     //freopen("in.txt","r",stdin);23     int t;24     scanf("%d",&t);25     while(t--)26     {27         memset(a,0,sizeof(a));28         int n;29         scanf("%d",&n);30         for(int i=0;i<n;i++)31         {32             scanf("%d%d",&a[i].x,&a[i].y);33             a[i].z=0;34         }35         sort(a,a+n,cmp);36         int count=0,length;37         for(int i=0;i<n;i++)38         {39             if(!a[i].z)40             {41                 count++;42                 length=a[i].x;43                 for(int j=i+1;j<n;j++)44                 {45                     if(!a[j].z)46                     {47                        if(a[j].x>=length)48                        {49                            a[j].z=1;50                            length=a[j].x;51                        }52                     }53 54                 }55             }56 57         }58         printf("%d\n",count);59     }60     return 0;61 }

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