POJ 1852 Ants

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字数统计: 479 | 阅读时长 ≈ 2

Ants

| Time Limit: 1000MS | | Memory Limit: 30000K |
| Total Submissions: 25649 | | Accepted: 10081 |

Description

An army of ants walk on a horizontal pole of length l cm, each with a constant speed of 1 cm/s. When a walking ant reaches an end of the pole, it immediatelly falls off it. When two ants meet they turn back and start walking in opposite directions. We know the original positions of ants on the pole, unfortunately, we do not know the directions in which the ants are walking. Your task is to compute the earliest and the latest possible times needed for all ants to fall off the pole.

Input

The first line of input contains one integer giving the number of cases that follow. The data for each case start with two integer numbers: the length of the pole (in cm) and n, the number of ants residing on the pole. These two numbers are followed by n integers giving the position of each ant on the pole as the distance measured from the left end of the pole, in no particular order. All input integers are not bigger than 1000000 and they are separated by whitespace.

Output

For each case of input, output two numbers separated by a single space. The first number is the earliest possible time when all ants fall off the pole (if the directions of their walks are chosen appropriately) and the second number is the latest possible such time.

Sample Input

2
10 3
2 6 7
214 7
11 12 7 13 176 23 191

Sample Output

4 8
38 207

Source

Waterloo local 2004.09.19

题解

每只蚂蚁相遇的时候会掉头，可以不管每只蚂蚁是否掉头，将其按原来的路行走来处理，这样就简单得多了。代码如下：

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#include <algorithm>
#include <stdio.h>
#include <iostream>
#include <string.h>
#include <cmath>
#define MAXN 1000005
int arr[MAXN] ;
using namespace std ;

int lontime( int len, int numb )
{
    int Maxt = 0 ;
    for ( int i = 0 ; i < numb ; i ++ )
    {
        Maxt = max(Maxt,max(arr[i],len-arr[i])) ;
    }
    return Maxt ;
}

int shrtime ( int len, int numb )
{
    int Mint = 0 ;
    for ( int i = 0 ; i < numb ; i ++ )
    {
        Mint = max(Mint,min(arr[i],len-arr[i])) ;
    }
    return Mint ;
}

int main()
{
    int n ;
    cin >> n ;
    while ( n -- )
    {
        memset(arr,0,sizeof(arr)) ;
        int len, numb ;  /// len -> 杆子长度, numb -> 蚂蚁数量
        cin >> len >> numb ;
        for ( int i = 0 ; i < numb ; i ++ )
        {
            cin >> arr[i] ;
        }
        cout << shrtime(len,numb) << " " << lontime(len,numb) << endl ;
    }
}