hdu 1051 Wooden Sticks 貪心

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3559    Accepted Submission(s): 1442

Problem DescriptionThere 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). 

 

InputThe 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. 

 

OutputThe output should contain the minimum setup time in minutes, one per line. 

 

Sample Input3 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//////////////////////////////////////////////////<br />//貪心策略很重要<br />//////////////////////////////////////////////////<br />#include<stdio.h><br />#include<iostream><br />using namespace std;<br />#include<algorithm><br />int f[5010];<br />struct wood<br />{<br /> int l,w;<br />}a[5010];<br />int comp(wood a,wood b)<br />{<br /> if(a.l==b.l)<br /> return a.w<b.w;<br /> return a.l<b.l;<br />}<br />int main()<br />{<br /> //freopen("a.txt","r",stdin);<br /> int n,t;<br /> scanf("%d",&t);<br /> while(t--)<br /> {<br /> scanf("%d",&n);<br /> int i,j;<br /> for(i=0;i<n;i++)<br /> {<br /> scanf("%d%d",&a[i].l,&a[i].w);<br /> f[i]=0;<br /> }<br /> sort(a,a+n,comp);<br /> int ans=0;<br /> for(i=0;i<n;i++)<br /> {<br /> if(f[i])continue;<br /> int temp=a[i].w;<br /> for(j=i+1;j<n;j++)<br /> {<br /> if(!f[j] && temp<=a[j].w)<br /> {<br /> f[j]=1;<br /> temp=a[j].w;<br /> }<br /> }<br /> ans++;<br /> }<br /> printf("%d/n",ans);<br /> }<br /> return 0;<br />}