HDU1051：Wooden Sticks

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
   
   
   
   

 

 

#include <iostream>
#include <algorithm>
using namespace std;

struct Node
{
    int head;
    int end;
    int flag;
} node[5005];

int cmp(struct Node a,struct Node b)
{
    if(a.head < b.head)
    return 1;
    else if(a.head == b.head)
    return a.end < b.end;
    return 0;
}

int main()
{
    int n,t;
    cin >> t;
    while(t--)
    {
        cin >> n;
        int i,j,sum = 0,cnt = 0;
        for(i = 0; i<n; i++)
        {
            cin >> node[i].head >> node[i].end;
            node[i].flag = 0;
        }
        sort(node,node+n,cmp);
        int ans = 0;
        for(i = 0; i<n; i++)
        {
            if(!node[i].flag)
            {
                node[i].flag = 1;
                ans++;
                int end = node[i].end;
                for(int j = i+1; j < n; j++)
                {
                    if(!node[j].flag && node[j].end >= end)
                    {
                        node[j].flag = 1;
                        end = node[j].end;
                    }
                }
            }
        }
        cout << ans << endl;
    }

    return 0;
}