HDU 1050（楼道搬桌子问题）（不是贪心解法，思路很新颖）

Moving Tables

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 40796    Accepted Submission(s): 13405

Problem Description

The famous ACM (Advanced Computer Maker) Company has rented a floor of a building whose shape is in the following figure.

The floor has 200 rooms each on the north side and south side along the corridor. Recently the Company made a plan to reform its system. The reform includes moving a lot of tables between rooms. Because the corridor is narrow and all the tables are big, only one table can pass through the corridor. Some plan is needed to make the moving efficient. The manager figured out the following plan: Moving a table from a room to another room can be done within 10 minutes. When moving a table from room i to room j, the part of the corridor between the front of room i and the front of room j is used. So, during each 10 minutes, several moving between two rooms not sharing the same part of the corridor will be done simultaneously. To make it clear the manager illustrated the possible cases and impossible cases of simultaneous moving.

For each room, at most one table will be either moved in or moved out. Now, the manager seeks out a method to minimize the time to move all the tables. Your job is to write a program to solve the manager’s problem.

 

Input

The input consists of T test cases. The number of test cases ) (T is given in the first line of the input. Each test case begins with a line containing an integer N , 1<=N<=200 , that represents the number of tables to move. Each of the following N lines contains two positive integers s and t, representing that a table is to move from room number s to room number t (each room number appears at most once in the N lines). From the N+3-rd line, the remaining test cases are listed in the same manner as above.

 

Output

The output should contain the minimum time in minutes to complete the moving, one per line.

 

Sample Input

3

4

10 20

30 40

50 60

70 80

2

1 3

2 200

3

10 100

20 80

30 50

 

Sample Output

10

20

30

 

Source

Asia 2001, Taejon (South Korea)

 

题目意思：

一层楼 400个房间，编号从1到400，分成两行，奇数一行，偶数一行，一条走廊在两排房间的中间，现在要从一共房间往另外一共房间搬桌子，由于走廊太窄，一次只能通过一张桌子，所以有重叠走廊段的桌子不能在同一个回合搬，问你搬完全部桌子，需要多少分钟？每个回合10分钟

 

解法：

搬桌子经过的走廊段不就是要经过这些走廊段中房间的门口吗？

400个房间，400个门口，两两个是相对的，所以看成200个门口

搬桌子经过该段就是经过该段的所有门口，经过的门口中经过次数最多门口的经过次数不就是我们需要的回合数吗？

注意：

 门口数组初始化全0，经过一次就++

找到门口中经过门口次数最大的门口中的经过次数就是我们需要的回合数

3，4是对门，看成同一个门口，这就是为什么

 a=(a+1)/2;
 b=(b+1)/2;

的原因

代码如下：

#include<bits/stdc++.h>
using namespace std;
#define max_v 205
int f[max_v];
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int n;
        scanf("%d",&n);
        memset(f,,sizeof(f));
        for(int i=; i<n; i++)
        {
            int a,b;
            scanf("%d %d",&a,&b);
            if(a>b)
            {
                int t=a;
                a=b;
                b=t;
            }
            a=(a+)/;
            b=(b+)/;
            for(int i=a;i<=b;i++)
            {
                f[i]++;
            }
        }
        int t=;
        for(int i=;i<max_v;i++)
        {
            if(t<f[i])
            {
                t=f[i];
            }
        }
        printf("%d\n",t*);
    }
    return ;
}