poj 1852 Ants(貪心)

Ants
Time Limit: 1000MS   Memory Limit: 30000K
Total Submissions: 14061   Accepted: 6134

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


題意:

有n只螞蟻在長爲l的木棒上爬行,當他們在木棒上相遇時,會朝相反的方向爬去,給你他們離起點的距離,當爬行到任意一個端點時,螞蟻掉落,

求全部螞蟻掉落的最長和最短時間

做法:

把全部螞蟻看作一樣的,當他們相遇時,看成相互穿過,這樣直接計算就行

#include <cstdio>
#include <cstring>
#include <iostream>
#define INF 0x3f3f3f
using namespace std;


int main(){
    int i,t,Min,Max,k,n,l;
    scanf("%d",&t);
    while(t--){
        scanf("%d%d",&l,&n);
        scanf("%d",&k);
        Min=min(k,l-k);
        Max=l-Min;
        for(i=2;i<=n;i++){
            scanf("%d",&k);
            Min=max(Min,min(k,l-k));
            Max=max(Max,max(k,l-k));
        }
        printf("%d %d\n",Min,Max);
    }
    return 0;
}


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