ZOJ Problem Set

ZOJ Problem Set - 1025

Wooden Sticks

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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

多少个递增子序列就多少分钟

AC代码：

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<string.h>
using namespace std;
struct Wood{
	int w,l;
};
bool cmp(Wood a,Wood b)
{
	if(a.w!=b.w)
	{
		return a.w<=b.w;
	}
	else
	{
		return a.l<=b.l;
	}
}
int main()
{
	int cas;
	cin>>cas; 
	while(cas--)
	{
		int n;
		Wood wood[10001];
		cin>>n;
		for(int i=0;i<n;i++)
		{
			cin>>wood[i].l>>wood[i].w;
		}
		sort(wood,wood+n,cmp);
		int minuts=0;
		bool *flag=new bool[n];
		memset(flag,0,sizeof(flag));
		for(int i=0;i<n;i++)
		{
			if(flag[i])continue;
			flag[i]=true;
			minuts++;
			int t=i;
			for(int j=i+1;j<n;j++)
			{
				if(wood[t].w<=wood[j].w&&wood[t].l<=wood[j].l&&!flag[j])
				{
					t=j;
					flag[j]=true;
				}
			}
		}
		cout<<minuts<<endl;
	} 
}