hdu 1051 Wooden Sticks 贪心

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3559    Accepted Submission(s): 1442

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 ////////////////////////////////////////////////// //贪心策略很重要 ////////////////////////////////////////////////// #include<stdio.h> #include<iostream> using namespace std; #include<algorithm> int f[5010]; struct wood { int l,w; }a[5010]; int comp(wood a,wood b) { if(a.l==b.l) return a.w<b.w; return a.l<b.l; } int main() { //freopen("a.txt","r",stdin); int n,t; scanf("%d",&t); while(t--) { scanf("%d",&n); int i,j; for(i=0;i<n;i++) { scanf("%d%d",&a[i].l,&a[i].w); f[i]=0; } sort(a,a+n,comp); int ans=0; for(i=0;i<n;i++) { if(f[i])continue; int temp=a[i].w; for(j=i+1;j<n;j++) { if(!f[j] && temp<=a[j].w) { f[j]=1; temp=a[j].w; } } ans++; } printf("%d/n",ans); } return 0; }