Wooden Sticks

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

Total Submission(s): 11244 Accepted Submission(s): 4627

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

题意是第一个3是3组数据，然后一个5是5根棍子。然后逐一输入其的长度和重量。

。题目是问怎么做这些棍子用时最少，在做棍子时。若后一根棍子。长度和重量都大于前

一根。则不用加时间。。

想法。。

拿第一组数据来说。

。

首先按长度以小到大排序：（1,4），（2，1），（3。 5）。（4， 9），（5,2）；

我们发现（2。 1）的重量太小，而（5， 2）的长度太长。这样排结果为3；

事实上这时，我们仅仅要把不满足的先标记起来。

。

则（1,4）。（3,5），（4,9） ———— （2,1），（5,2）

但我们这么排，也就是题目给出的顺序，结果就为2；也就是最优。


#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

#include<vector>

#include<queue>

#include<sstream>

#include<cmath>

using namespace std;

#define M 100500

struct node

{

    int lenth;

    int weight;

    int k;

} Q[M];

bool cmp ( node a, node b )

{

    if(a.lenth==b.lenth)

        return a.weight<b.weight;

    else

        return a.lenth<b.lenth;

}

int main()

{

    int t;

    int n;

    scanf("%d", &t);

    while( t-- )

    {

        scanf("%d", &n);

        for(int i=0; i<n; i++)

        {

            scanf("%d%d", &Q[i].lenth, &Q[i].weight);

            Q[i].k= 1;

        }

        sort( Q, Q+n, cmp );

        int ans = 0;

        for(int i=0; i<n-1; i++)

        {

            if(!Q[i].k)

                continue;

            int t = Q[i].weight;

            for(int j = i+1; j<n; j++)

                if(Q[j].weight>=t &&Q[j].k==1 )

                {

                    ans++;

                    Q[j].k=0;

                    t = Q[j].weight;

                }

        }

        printf("%d\n", n-ans);

    }

    return 0;

}

巴特西

HDU 1051： Wooden Sticks（贪心）

Wooden Sticks

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