Moving Tables 贪心

Moving Tables

题目连接

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 34008    Accepted Submission(s): 11157

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

题意

一个走廊两边是房间，房间里有大桌子，走廊的宽度只能装下一个桌子，现给出一系列要移动桌子的房间号（i ----> j）从i房间移动到j房间，每移动一次都要花费十分钟，问 一共最少需要多少时间？

分析

这种问题就是贪心问题，求所有的区间最大的重叠度，但是要注意房间的位置与房间号的关系，(房间号+1)/2就是对应的房间的坐标。还有就是输入的房间号不一定是按照从小到大的顺序给出的。

代码

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string.h>
using namespace std;
int main()
{
    int n;
    scanf("%d",&n);
    while(n--)
    {
        int a[250];
        memset(a,0,sizeof(a));
        int m;
        scanf("%d",&m);
        int max=-1;
        for(int i=0; i<m; i++)
        {
            int in=0;
            int out=0;
            int temp;
            scanf("%d%d",&in,&out);
            if(in>out)
            {
                temp=in;
                in=out;
                out=temp;
            }
            in=(in+1)/2;
            out=(out+1)/2;
            for(int i=in; i<=out; i++)
                a[i]++;
            if(out>max)
                max=out;
        }
        int  value=-1;
        for(int i=0; i<=max; i++)
        {
            if(a[i]>value)
                value=a[i];
        }
        printf("%d\n",value*10);
    }
    return 0;
}