poj 1852 Ants

Ants

Time Limit: 1000MS		Memory Limit: 30000K
Total Submissions: 33420		Accepted: 12441

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

對於最短期，全部螞蟻都朝向較近的端點走會比較好，這種狀況下不會發生兩隻螞蟻相遇的狀況，並且也不可能在比此種狀況更短的時間內走到杆子的端點。

考慮最長時間，假如兩隻螞蟻相遇，兩隻螞蟻都朝相反的方向走，而咱們能夠認爲這兩隻螞蟻保持原樣交錯而行。能夠認爲每隻螞蟻都是獨立運動的。

 1 #include <algorithm>
 2 #include <cstdio>
 3 using namespace std;
 4 
 5 int main(){
 6     int test, l, n;
 7     scanf("%d", &test);
 8     while(test--){
 9         int least = 0, most = 0;
10         scanf("%d %d", &l, &n);
11         int x;
12         for(int i = 0; i < n; i++){
13             scanf("%d", &x);
14             least = max(least, min(x, l - x));
15             most = max(most, max(x, l - x));
16         }
17         printf("%d %d\n", least, most);
18     }
19     return 0;
20 } 

 

越努力，越幸運