hdu 1051 Wooden Sticks

最新推荐文章于 2025-09-06 09:33:29 发布

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原文链接：http://www.cnblogs.com/caiyishuai/p/8434704.html

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#java

本文探讨了一道经典的编程问题——如何确定加工一系列木棍所需的最小准备时间。通过寻找最长的非递减子序列来解决该问题，文章提供了一个详细的算法实现方案。

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 23703 Accepted Submission(s): 9625

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

类似最少拦截系统，求最长不降子序列

 1 #include <iostream>
 2 #include <cstring>
 3 #include <string>
 4 #include <algorithm>
 5 using namespace std;
 6 struct node
 7 {
 8     int l, w;
 9 }a[5005];
10 bool cmp(node x, node y)
11 {
12     if (x.l == y.l)
13         return x.w < y.w;
14     return x.l < y.l;
15 }
16 int main()
17 {
18     int dp[5005];
19     int t;
20     cin >> t;
21     while (t--)
22     {
23         int n;
24         cin >> n;
25         int i;
26         for (i = 1; i <= n; i++)
27         {
28             cin >> a[i].l >> a[i].w;
29             dp[i] = 1;
30         }
31         sort(a + 1, a + 1 + n, cmp);
32         int j;
33         int k = 1;
34         int ans =0;
35         for (i = 2; i <= n; i++)
36         {
37             for (j =1; j<=i; j++)
38             {
39                 if (a[j].w>a[i].w)//前面有一个比它要大
40                 {
41                     dp[i] =max(dp[i], dp[j]+1);
42                 }
43             }
44             ans = ans > dp[i] ? ans : dp[i];
45         }
46         cout << ans << endl;
47     }
48     return 0;
49 }