Wooden Stickshttp://acm.hdu.edu.cn/game/entry/problem/show.php?chapterid=1§ionid=3&problemid=16 |
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) |
Total Submission(s): 1480 Accepted Submission(s): 595 |
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.
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Output
The output should contain the minimum setup time in minutes, one per line.
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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
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Sample Output
2
1
3
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Source
Asia 2001, Taejon (South Korea)
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#include<stdio.h> #include<stdlib.h> struct node{ int len,weight; int tag; }a[5005]; int cmp(const void *a,const void *b){ node c=*(node *)a; node d=*(node *)b; if(c.len==d.len) return c.weight-d.weight; return c.len-d.len; } int main(){ int t; scanf("%d",&t); while(t--){ int n; scanf("%d",&n); int i; for(i=0;i<n;i++){ scanf("%d%d",&a[i].len,&a[i].weight); a[i].tag=0; } qsort(a,n,sizeof(a[0]),cmp); int ans=0,flag; int j,cnt=0; a[0].tag=1; while(cnt<n){ ++ans; for(i=cnt+1,j=cnt,flag=1;i<n;i++){ if(a[i].tag) continue; if(a[j].len<=a[i].len && a[j].weight<=a[i].weight){ j=i; a[i].tag=1; }else{ if(flag){ flag=0; cnt=i; } } } if(flag) break; } printf("%d\n",ans); } return 0; }