1.3.7 Wooden Sticks

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 2565 Accepted Submission(s): 995

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 2 1 3

Source Asia 2001, Taejon (South Korea) #include <cstdio> #include <string.h> #include <math.h> #include <string> #include <iostream> #include <algorithm> using namespace std; const int N=1000+1; struct hehe{ int first,second; }a[5005]; bool cmp(hehe a,hehe b) { return a.first<=b.first; } int main() { int t,i,n,sum,len; int last1,last2; cin>>t; while(t--){ cin>>n; sum=0; for(i=0;i<n;i++) cin>>a[i].first>>a[i].second; sort(a,a+n,cmp); while(n!=0){ sum++; len=0; last1=a[len].first,last2=a[len].second; for(i=1;i<n;i++){ if(a[i].first>=last1&&a[i].second>=last2) { last1=a[i].first,last2=a[i].second; } else{ a[len].first=a[i].first; a[len].second=a[i].second; len++; } } n=len; } cout<<sum<<endl; } return 0; }