Wooden Sticks
Time Limit: 1000MS |
|
Memory Limit: 10000K |
Total Submissions: 20948 |
|
Accepted: 8875 |
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
Source
Taejon 2001
贪心即可;
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
struct Stick
{
int length;
int weight;
}stick[5001];
bool cmp(const Stick& a,const Stick& b)
{
if(a.length==b.length)
return a.weight<b.weight;
return a.length<b.length;
}
bool vis[5001];
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
int n;
scanf("%d",&n);
for(int i=0;i<n;++i)
{
scanf("%d %d",&stick[i].length,&stick[i].weight);
}
sort(stick,stick+n,cmp);
memset(vis,0,sizeof(vis));
int ans=0;
int temp;
for(int i=0;i<n;++i)
{
temp=stick[i].weight;
if(!vis[i])
{
for(int j=i+1;j<n;++j)
{
if(temp<=stick[j].weight&&!vis[j])
{
vis[j]=1;
temp=stick[j].weight;
}
}
++ans;
}
}
printf("%d\n",ans);
}
return 0;
}