Wooden Sticks

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 27437		Accepted: 11926

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

思路：这道题并不难，只是要把题目想清楚
但是现在由于 POJ 维修不能提交，明天再提交了看

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <iostream>
 5 #define MAX_N 10005
 6 using namespace std;
 7 
 8 int n;
 9 
10 struct Wood
11 {
12     int l;
13     int w;
14     int used;
15 }wood[MAX_N];
16 
17 bool cmp(const Wood &a,const Wood &b){
18     if(a.l==b.l) return a.w<b.w;
19     else    return a.l<b.l;
20 }
21 
22 int main(void){
23     int T;
24     scanf("%d",&T);
25     for(int m=0;m<T;m++){
26         int ans=0;
27         scanf("%d",&n);
28         for(int j=0;j<n;j++){
29             scanf("%d",&wood[j].l);
30             scanf("%d",&wood[j].w);
31             wood[j].used=0;
32         }
33         sort(wood,wood+n,cmp);
34 
35         for(int i=0;i<n;i++){
36             int last=wood[i].w;
37             if(!wood[i].used){
38                 for(int j=i+1;j<n;j++){
39                     if(wood[j].w>=last&&(!wood[j].used)){
40                         wood[j].used=1;
41                         last=wood[j].w;
42                     }
43                 }
44                 ans++;
45             }
46         }
47         printf("%d\n",ans);
48     }
49 
50     return 0;
51 }

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