1/21集训二 模拟+贪心 F.（贪心 处理有长度和重量的木棍，求最小处理机器的次数）Wooden Sticks

1/21集训二 模拟+贪心

F.（贪心 处理有长度和重量的木棍，求最小处理机器的次数）Wooden Sticks

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

题意：
知道它们的长度和重量，每当要处理更短或更轻的木棍时，都需要花1分钟准备，问至少要多久。

思路：
将木棍按照长度排列，若长度相同则按照重量排列。
从第一根最小的木棍开始，往后遍历，寻找比它大的木棍，并将这些木棍用vis标记起来，那么这些木棍在用机器处理的时候，就不需要在调整机器。
这样多次遍历，就可以将整个木棍序列分成几个子序列，每一个子序列都是递增的，那么我们就可以根据这几个子序列来判断处理时间了。

#include 
#include 
#include 
#include 
#include 
using namespace std;
#define MAXN 5005

struct Node
{
    int l;
    int w;
    bool vis;
};

bool cmp(Node a, Node b)
{
    if(a.l != b.l)
        return a.l < b.l;
    else
        return a.w < b.w;
}

int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n, ans = 0;
        struct Node node[MAXN];
        cin>>n;
        for(int i = 0; i < n; i++)
        {
            cin>>node[i].l>>node[i].w;
            node[i].vis = false;
        }
        sort(node, node + n, cmp);
        for(int i = 0; i < n; i++)
        {
            int we;
            if(!node[i].vis)
            {
                we = node[i].w;
                ans++;
                node[i].vis = true;
                for(int j = i + 1; j < n; j++)
                {
                    if(!node[j].vis && node[j].w >= we)
                    {
                        we = node[j].w;
                        node[j].vis = true;
                    }
                }
            }
        }
        cout<return 0;
}