poj1065 Wooden Sticks

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 ( 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.

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

解题思路：看到题目，想到了排序了，然后往后走，只要遇到不符合的，就加一，但结果大了，
最后改成从头走到位，符合条件的标记，然后换起始点，再走，一直下去可解。
代码如下： 

#include<iostream>
usingnamespacestd;
#defineMAX5005
inttime,n;
structdata
{
intl;
intw;
};
datainfo[MAX];


intcmp(constvoid*a,constvoid*b)
{
structdata*c=(data*)a;
structdata*d=(data*)b;
if(c->l!=d->l)
returnc->l-d->l;
else
returnc->w-d->w;
}

voidWooden_Sticks_Greedy()
{
qsort(info,n,sizeof(info[0]),cmp);    //对结构体进行二级从小到大派讯
intmark[MAX]={0};
time=0;
inttemp;
for(inti=0;i<n;i++)
{
if(mark[i]==0)
{
temp=info[i].w;
for(intj=i+1;j<n;j++)
{
if(info[j].w>=temp&&mark[j]==0)
{
temp=info[j].w;
mark[j]=1;
}
}
time++;
}
}
cout<<time<<endl;
}

intmain()
{
inti,test;
cin>>test;
while(test--)
{
cin>>n;
for(i=0;i<n;i++)
cin>>info[i].l>>info[i].w;
Wooden_Sticks_Greedy();
}
return0;
}