zoj 1025 Wooden Sticks

Wooden Stickshttp://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=1025

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Time Limit: 2 Seconds      Memory Limit: 65536 KB

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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

一开始一直把题目理解错了。。。。以为选一个wooden l w,后面的只要l*>=l&&w*>w,就不用消耗时间

原本题目意思是：先选一个wooden1 l w,紧跟后面的wooden2 l* w*,只要l*>l&&w*>w,wooden2就不要消耗时间，在后面的wooden3要跟wooden2 的 l w 比较，而不是 wooden1,

此题可以先根据 l进行排序，然后用贪心

#include<iostream>
#include<algorithm>
#include<string.h>
#include<stdlib.h>
using namespace std;
struct as
{
    int l;
    int w;
}p[5010];
int cmp (as a,as b)
{
   if(a.l>b.l)
    return 0 ;
   else
    if(a.l==b.l)
    {
       if(a.w>=b.w)
        return 0;
       else
        return 1;
    }
    else
        return 1;
}
int main()
{
    int t,n,i,j,q[5010],pos;
    cin >> t;
    while( t-- )
    {
        memset(q,0,sizeof(q));
        cin >>n ;
        for( i=0;i<n;i++ )
            cin>>p[i].l>>p[i].w;
        sort ( p,p+n,cmp );
        for( i=0;i<n;i++ )
        if(q[i]==0)
        {
            pos=i;
            for(j=i+1;j<n;j++)
            if(q[j]==0&&p[j].w>=p[pos].w)
            {
                q[j]=1;pos=j;
            }
        }
        int sum=0;
        for(i=0;i<n;i++)
            if(q[i]==0)
            sum++;
            cout<<sum<<endl;
    }
}