HDU 1051 wooden sticks
Wooden Sticks
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 11619 Accepted Submission(s): 4800
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
Sample Output
Source
Asia 2001,Taejon(South Korea)テーマリンク :http://acm.hdu.edu.cn/showproblem.php?pid=1051 テーマの大意 :n本の木の棒があって、第1本を加工して1時間を必要として、もし後の1本の長さと重量がすべて前の1本に等しいならば、機械は余分な時間を費やしません ここでn本の木の棒の長さと重量を与えて、これらの木の棒を加工するのに最も必要な時間のテーマの分析を求めます :貪欲な策略を採用して、まず木の棒の長さあるいは重量に対して並べ替えて、(私は先に長さに対して小さいから大きいまで並べ替えて、先に重量を並べ替えても同じで、小さいから大きいまであるいは大きいから小さいまで構わないが、長さと重量の並べ替え方案は必ず統一しなければならない)、長さの並べ替えが終わってから重量に対して並べ替えて、1組の重量の単調な増加(減少)の集合を見つけて標識をして、最後に求めた集合の数が問題の答えである.
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 11619 Accepted Submission(s): 4800
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)テーマリンク :http://acm.hdu.edu.cn/showproblem.php?pid=1051 テーマの大意 :n本の木の棒があって、第1本を加工して1時間を必要として、もし後の1本の長さと重量がすべて前の1本に等しいならば、機械は余分な時間を費やしません ここでn本の木の棒の長さと重量を与えて、これらの木の棒を加工するのに最も必要な時間のテーマの分析を求めます :貪欲な策略を採用して、まず木の棒の長さあるいは重量に対して並べ替えて、(私は先に長さに対して小さいから大きいまで並べ替えて、先に重量を並べ替えても同じで、小さいから大きいまであるいは大きいから小さいまで構わないが、長さと重量の並べ替え方案は必ず統一しなければならない)、長さの並べ替えが終わってから重量に対して並べ替えて、1組の重量の単調な増加(減少)の集合を見つけて標識をして、最後に求めた集合の数が問題の答えである.
#include <cstdio>
#include <algorithm>
using namespace std;
int const MAX = 5000 + 5;
struct STICK //
{
int l;
int w;
}sticks[MAX];
int flag[MAX]; //
bool cmp(STICK a, STICK b)
{
if(a.l != b.l)
return a.l < b.l;
else
return a.w < b.w;
}
int main()
{
int num,min = 0,T;
scanf("%d",&T);
while(T--)
{
scanf("%d",&num);
for(int i = 0; i < num; i++)
{
scanf("%d%d",&sticks[i].l,&sticks[i].w);
flag[i] = 0; //
}
sort(sticks,sticks + num,cmp); //
int cnt = 0;
for(int i = 0; i < num; i++)
{
if(flag[i]) // ( )
continue;
min = sticks[i].w;
for(int j = i + 1; j < num; j++)
{
if(min <= sticks[j].w && !flag[j]) //
{
min = sticks[j].w;
flag[j] = 1;
}
}
cnt++; // cnt
}
printf("%d
",cnt);
}
}