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HDU 1051 Wooden Sticks【贪心+排序】

2024-07-29 05:54:00   219人阅读

/*
中文题目 木头
中文翻译-大意 加工第一个木头要调试机器，所以要一分钟，后面的木头在长度和重量上都要大于等于前一个木头，才不要调试机器，否则要调试机器，再花费一分钟
解题思路：先将木头的长度按升序排序，后面质量发生冲突的地方就要在之后重新安排一下
解题人：lingnichong
解题时间：2014-10-25 16:33:10
解题体会：一个括号的丢失，就导致错了一大片
*/

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12150    Accepted Submission(s): 5034


Problem 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 (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
 

Sample Output
2
1
3
 

Source
Asia 2001, Taejon (South Korea)
 


#include<stdio.h>
#include<algorithm>
using namespace std;

int temp[5005];//用来记录不同序列数的起点

struct node
{
	int a,b;
}arr[5005];

int cmp(node x,node y)//排序：让长度相同的木头，质量小的在前面
{
	if(x.a == y.a)
		return x.b<y.b;
	return x.a<y.a;
}

int main()
{
	int T,N,i,j;
	int time;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%d",&N);
		for(i=0;i<N;i++)
			scanf("%d%d",&arr[i].a,&arr[i].b);
		sort(arr,arr+N,cmp);
			
		time=1;
		temp[0]=arr[0].b;//先把排序后第一个点设为起点
		for(i=1;i<N;i++)
		{
			for(j=0;j<time;j++)
			{
				if(arr[i].b >= temp[j])//更新一下数据，使后面质量大的数覆盖前一个质量数
				{
					temp[j]=arr[i].b;
					break;
				}
			}
			if(j==time)//当所有起点都不满足，就重新再安排一个起点
			{
				if(arr[i].b < temp[j-1])
				{
					temp[j]=arr[i].b;
					time++;
				}
			}
		}
		printf("%d\n",time);		
	}
	return 0;
}







HDU 1051 Wooden Sticks【贪心+排序】


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