Wooden Sticks
| Time Limit: 1000MS |
|
Memory Limit: 10000K |
| Total Submissions: 19992 |
|
Accepted: 8431 |
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
Source
1 #include <stdio.h>
2 #include <algorithm>
3
4 struct st {
5 int l, w, vis;
6 bool operator<(const st&c)const {
7 return l==c.l?w<c.w:l<c.l;
8 }
9 }stick[5001];
10
11 int n;
12 void read() {
13 scanf("%d", &n);
14 for(int i=0; i<n; i++) {
15 scanf("%d%d", &stick[i].l, &stick[i].w);
16 stick[i].vis = 0;
17 }
18 }
19
20 void find(int i) {
21 int k = i;
22 for(int j=i+1; j<n; j++)
23 if(!stick[j].vis)
24 if(stick[k].w<=stick[j].w) {
25 stick[j].vis = 1;
26 k=j;
27 }
28 }
29
30 void work() {
31 int res = 0;
32 std::sort(stick, stick+n);
33 for(int i=0; i<n; i++) {
34 if(!stick[i].vis) {
35 stick[i].vis = 1;
36 ++res;
37 find(i);
38 }
39 }
40 printf("%d\n", res);
41 }
42
43 int main() {
44 int T, n;
45 scanf("%d", &T);
46 while(T--) {
47 read();
48 work();
49 }
50 return 0;
51 }
