HDOJ 1051. Wooden Sticks 贪心 结构体排序

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

 

题目

一堆n根木棍。每个棒的长度和重量是预先已知的。这些木棒将由木工机械一一加工。机器需要准备一些时间（称为准备时间）来准备处理木棍。设置时间与清洁操作以及更换机器中的工具和形状有关。木工机械的准备时间如下： 

　　（a）第一个木棍的准备时间为1分钟。
　　（b）在处理长度为l和重量为w的棒之后，如果l <= l'并且w <= w'，则机器将不需要设置长度为l'和重量为w'的棒的设置时间。否则，将需要1分钟进行设置。
您将找到处理给定的n根木棍的最短准备时间。例如，如果您有五根长度和重量对分别为（9，4），（2，5），（1、2），（5、3）和（4，1）的摇杆，则最小设置时间应该是2分钟，因为有对（4，1），（5，3），（9，4），（1，2），（2，5）对的序列。

输入值

输入包含T个测试用例。在输入文件的第一行中给出了测试用例的数量（T）。每个测试用例由两行组成：第一行具有整数n，1 <= n <= 5000，代表测试例中木棍的数量，第二行包含2n个正整数l1，w1，l2， w2，...，ln，wn，每个大小最大为10000，其中li和wi分别是第i个木棍的长度和重量。2n个整数由一个或多个空格分隔。

输出量

输出应包含以分钟为单位的最短建立时间，每行一条。

样本输入

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 

样本输出

2

1

3

 

作者描述
其实这道题和友好城市（https://www.luogu.com.cn/problem/P2782）有类似的地方
我们只需要借助结构体......就可以了
这道题没什么好说的，直接上代码

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=5010;
struct Node{
    int l,w;
}e[N];
int n,T;
int f[N];

bool cmp(Node A,Node B){
    if(A.l==B.l)return A.w<B.w;
    else return A.l<B.l;
}

int main(){
    scanf("%d",&T);
    while(T--){
        memset(f,0,sizeof(f));
        memset(e,0,sizeof(e));
        scanf("%d",&n);
        for(int i=1;i<=n;i++){
            scanf("%d%d",&e[i].l,&e[i].w);
        }
        
        sort(e+1,e+1+n,cmp);int ans=1;
        for(int i=1;i<=n;i++){
            f[i]=1;
            for(int j=1;j<i;j++){
                if(e[i].w<e[j].w&&f[i]<f[j]+1){
                    f[i]=f[j]+1;
                    ans=max(ans,f[i]);
                }
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}