HDU-1051Wooden Sticks

      Wooden Sticks

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

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

 

Hint

 

题解

    标准的贪心，将长度排序，然后进行筛选。自己的问题是排序时没注意到长度相等时重量不同的情形，应该将这种情况同样排序。

 

代码

#include<iostream>
#include<cstdio>
#include<memory.h>
using namespace std;

int l[5005],w[5005],flag[5005];

void sort1(int* a,int* b,int n)
{
    int t;
    for(int i=1;i<=n;i++){
        for(int j=i+1;j<=n;j++){
            if(a[i]>a[j]){
                t=a[i];
                a[i]=a[j];
                a[j]=t;
                t=b[i];
                b[i]=b[j];
                b[j]=t;
            }
            if(a[i]==a[j]){
                if(b[i]>b[j]){
                    t=a[i];
                    a[i]=a[j];
                    a[j]=t;
                    t=b[i];
                    b[i]=b[j];
                    b[j]=t;
                }
            }
        }
    }
}

int main()
{
    int T,n;
    cin >>T;
    while(T--){
        cin >>n;
        int count1=0;
        memset(flag,0,sizeof(flag));
        for(int i=1;i<=n;i++)
            scanf("%d %d",&l[i],&w[i]);
        sort1(l,w,n);
        //for(int i=1;i<=n;i++) cout <<l[i]<<w[i]<<endl;
        flag[1]=1;
        int beg=1;
        while(beg<=n){
            count1++;
            int i,j,s;
            for(i=beg+1,j=beg,s=1;i<=n;i++){
                if(flag[i]) continue;
                if(l[j]<=l[i]&&w[j]<=w[i]){
                    flag[i]=1;
                    j=i;
                }
                else {
                    if(s){
                        beg=i;
                        s=0;
                    }
                }
            }
            if(s) break;
        }
        cout <<count1<<endl;
    }
}