hdu 1051 woolen sticks（贪心）

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 11644    Accepted Submission(s): 4817

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

213

 

Source

Asia 2001, Taejon (South Korea)

 

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思路：贪心 注意最后统计的时候 别忘了更新值

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;struct Node{int h,w;bool operator <(const Node &k)const{   if(h!=k.h)   return h<k.h;   else   return w<k.w;}};Node a[50004];int vis[50004];int main(){int t,n;int i,j;scanf("%d",&t);while(t--){scanf("%d",&n);for(i=0;i<n;i++){scanf("%d %d",&a[i].h,&a[i].w);}sort(a,a+n);memset(vis,0,sizeof(vis));//for(i=0;i<n;i++){//printf("%d %d\n",a[i].h,a[i].w);//}int cnt=0;int we;     for(i=0;i<n;i++){     if(!vis[i]){         vis[i]=1;         cnt++;         we=a[i].w;       for(j=i+1;j<n;j++){     if(!vis[j]&&we<=a[j].w){     vis[j]=1;     we=a[j].w;//注意更新we的值      }        } }// for(int k=0;k<n;k++)// printf("%d ",vis[k]);// cout<<endl;     }cout<<cnt<<endl;}return 0;}