Zoj 1025 Wooden Sticks

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

Output for the Sample Input

2
1
3

排序之后暴力求解就OK了

#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

struct Node{
	int L,W;
}num[10000];

int flag[10000];

bool cmp(Node a,Node b)
{
	if(a.L!=b.L)
		return a.L<b.L;
	return a.W<b.W;
}

int main()
{
	int T,n;
	int i,cnt,ok;
	Node tmp;

	scanf("%d",&T);

	while(T--)
	{
		scanf("%d",&n);
		for(i=1;i<=n;i++)
			scanf("%d%d",&num[i].L,&num[i].W);
		sort(num+1,num+1+n,cmp);
/*		printf("\n");
		for(i=1;i<=n;i++)
			printf("%d %d\n",num[i].L,num[i].W);
		printf("\n");
*/		memset(flag,0,(n+100)*sizeof(flag[0]));
		cnt=0;
		ok=1;
		while(ok)
		{
			ok=0;
			for(i=1;i<=n;i++)
			{
				if(ok==0 && flag[i]==0)
				{
					ok=1;
					flag[i]=1;
					cnt++;
					tmp=num[i];
					continue;
				}
				if(flag[i]==0 && tmp.L<=num[i].L && tmp.W<=num[i].W)
				{
					tmp=num[i];
					flag[i]=1;
				}
			}
		}
		printf("%d\n",cnt);
	}

	return 0;
}