hdu 4281 Judges' response(多旅行商&DP)
Judges' response
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 454 Accepted Submission(s): 256
Problem Description
The contest is running and the judges is busy watching the progress of the contest. Suddenly, N - 1 (N <= 16) contestants hand up their hand at the same time. The judges should go to answer the contestants' question one by one. The judges already foresee that answering contest i's question would cost Ci minutes. In order to serve all the contestant, each judges is assigned to serve some subset of the contestants. As the judges have limited patience, each one of them can serve the contestants for no more than M minutes.
You are asked to solve two problems:
1. At least how many judges should be sent so that they can serve all the contestants? (Because the judges have limited patience, each one of them cannot serve too many contestants.)
2. If there are infinite number of judges, how to assign the route for each judge so that the sum of their walking time is minimized? Each contestant i is reside in place (xi, yi), the judges are in place (x1, y1). Assuming the walking speed of the judge is 1.
You are asked to solve two problems:
1. At least how many judges should be sent so that they can serve all the contestants? (Because the judges have limited patience, each one of them cannot serve too many contestants.)
2. If there are infinite number of judges, how to assign the route for each judge so that the sum of their walking time is minimized? Each contestant i is reside in place (xi, yi), the judges are in place (x1, y1). Assuming the walking speed of the judge is 1.
Input
There are several test cases, Each case begin with two integer N, M(with the meaning in the above context, 2 <= N <= 16, 0 <= M <= 100000).
Then N lines follow and line i will contain two numbers x, y(0 <= x, y <= 1000), indicating the coordinate of place i.
Then another N lines follow and line i will contain numbers Ci(0 <= Ci <= 1000), indicating the time to solve contestant i's question. C1 will 0 as place 1 is for the judges.
The distance between place i and place j is defined as ceil(sqrt((xi - xj) ^ 2 + (yi - yj) ^ 2)). (ceil means rounding the number up, e.g. ceil(4.1) = 5)
Then N lines follow and line i will contain two numbers x, y(0 <= x, y <= 1000), indicating the coordinate of place i.
Then another N lines follow and line i will contain numbers Ci(0 <= Ci <= 1000), indicating the time to solve contestant i's question. C1 will 0 as place 1 is for the judges.
The distance between place i and place j is defined as ceil(sqrt((xi - xj) ^ 2 + (yi - yj) ^ 2)). (ceil means rounding the number up, e.g. ceil(4.1) = 5)
Output
For each case, output two numbers. The first is the minimum number of judges for question 1. The second is the minimum sum of walking time for question 2.
If it's impossible to serve all the contestants, please output -1 -1 instead.
If it's impossible to serve all the contestants, please output -1 -1 instead.
Sample Input
3 3
0 0
0 3
0 1
0
1
2
3 2
0 0
0 3
0 1
0
1
2
3 1
0 0
0 3
0 1
0
1
2
16 35
30 40
37 52
49 49
52 64
31 62
52 33
42 41
52 41
57 58
62 42
42 57
27 68
43 67
58 48
58 27
37 69
0
19
30
16
23
11
31
15
28
8
8
7
14
6
19
11
Sample Output
1 6
2 8
-1 -1
8 467
Source
Recommend
题意：
给定n个地点的坐标和每个地点的权值，点有点权边有边权。现在裁判在点1，需要分配这些裁判到这些点去，已知每个裁判能够到点权之和不大于m，而且一个点不能由两个裁判访问。现在给出两个问题，1、最少几个裁判可以覆盖所有点 2、给定无数个裁判，怎么样访问这些点使得总边权和最小，裁判访问完必须回到1点，而且一个裁判访问的点权之和不能超过m。
思路:
第一个问题很简单。由于有问题的人最多16个。可以把一个裁判可以解决的问题壮压。对应位置为1表示该裁判会解决对应问题。然后这就抽象成一个物品了。然后背出全为1的状态就行了。比赛时就因为第一问简单就傻乎乎的写了。看懂第二问时就凌乱了。于是参考了下大神的博客，才知道那是MTSP(多旅行商问题)。不过用DP的方法极限数据时用了12s。。。只能说题目数据太水了。。。不过第二问的思路蛮经典的。又一次进行了抽象。把一个裁判从解决完问题到回到1点的最短用时抽象为一个物品。然后一样的背包。对于最短用时可以壮压DP求出。
详细见代码：
#include<algorithm>
#include<iostream>
#include<string.h>
#include<sstream>
#include<stdio.h>
#include<math.h>
#include<vector>
#include<string>
#include<time.h>
#include<queue>
#include<set>
#include<map>
using namespace std;
const int INF=0x3f3f3f3f;
const int maxn=100010;
int n,m,cnt,ans1,ans2,lim;
int x[20],y[20],c[20];
int state[1<<17];//存可行状态
int dp[1<<17],dis[20][20];//dp处理最少的裁判数
int dpp[20][1<<17],mind[1<<17];//dpp[i][j]表示当前在i点。访问状态为j时的最小距离。
//clock_t st,ed; //mind[i]表示完成访问状态i所走的最少路程
//double dur;
bool isok(int st)//判断一个裁判的可行状态。抽象为一个物品。
{
int i=0,sum=0;
while(st)
{
if(st&1)
sum+=c[i];
st>>=1;
i++;
}
if(sum<=m)
return true;
else
return false;
}
void getDist()//求距离
{
int i,j,xx,yy;
for(i=0;i<n;i++)
{
dis[i][i]=0;
for(j=i+1;j<n;j++)
{
xx=x[j]-x[i];
yy=y[j]-y[i];
dis[i][j]=dis[j][i]=ceil(sqrt((double)(xx*xx+yy*yy)));
}
}
}
void TSP()//典型的单旅行商问题
{
int s,j,ns;
memset(dp,0x3f,sizeof dp);
dp[0]=0;
for(s=0;s<lim;s++)
{
if(dp[s]==INF)
continue;
for(j=0;j<cnt;j++)
{
if(s&state[j])
continue;
ns=s|state[j];
dp[ns]=min(dp[ns],dp[s]+1);
}
}
ans1=dp[lim-1];
}
void MTSP()//多旅行商
{
int i,j,k,s,ns;
getDist();
memset(dpp,0x3f,sizeof dpp);
memset(mind,0x3f,sizeof mind);
dpp[0][1]=0;//0必须为起点
for(i=0;i<cnt;i++)
{
s=state[i];
for(j=0;j<n;j++)
{
if(s&(1<<j)&&dpp[j][s]!=INF)//枚举起点
{
mind[s]=min(mind[s],dpp[j][s]+dis[j][0]);//把一个裁判完成访问状态再回到0点抽象为一个物品
for(k=0;k<n;k++)
{
if(s&(1<<k))
continue;
ns=s|(1<<k);//ns状态不一定有效
dpp[k][ns]=min(dpp[k][ns],dpp[j][s]+dis[j][k]);
}
}
}
}
for(s=1;s<lim;s++)//大神的方法。感觉(s-1)&比较巧妙。得到的状态一定是1比s少的状态。
{
if(s&1) //递推就是从1少的状态推1多的状态
{
for(ns=(s-1)&s;ns;ns=(ns-1)&s)
mind[s]=min(mind[s],mind[ns|1]+mind[(s-ns)|1]);
}
}
/*这是我的DP方法极限数据18s。。汗。。
for(s=0;s<lim;s++)//把抽象后的物品直接背包
{
if(mind[s]==INF)//由于mind原本的值不会影响后面结果。所以不用初始化
continue;
for(i=0;i<cnt;i++)
{
if(state[i]&1)
{
if((s-1)&(state[i]-1))
continue;
ns=s|state[i];
mind[ns]=min(mind[ns],mind[s]+mind[state[i]]);
}
}
}
*/
ans2=mind[lim-1];
}
int main()
{
int i,ma;
while(~scanf("%d%d",&n,&m))
{
for(i=0;i<n;i++)
scanf("%d%d",&x[i],&y[i]);
ma=0;
for(i=0;i<n;i++)
{
scanf("%d",&c[i]);
ma=max(ma,c[i]);
}
if(ma>m)
{
printf("-1 -1\n");
continue;
}
//st=clock();
cnt=0,lim=1<<n;
for(i=0;i<lim;i++)
if(isok(i))
state[cnt++]=i;
TSP();
MTSP();
//ed=clock();
//dur=(double)(ed-st)/CLOCKS_PER_SEC;
//printf("time: %.2lf\n",dur);
printf("%d %d\n",ans1,ans2);
}
return 0;
}
/*
3 3
0 0
0 3
0 4
0
2
2
3 2
0 0
0 3
1 0
0
1
2
3 1
0 0
0 3
0 1
0
1
2
4 9
1 2
1 3
2 1
3 1
0
5
6
4
16 3500
30 40
37 52
49 49
52 64
31 62
52 33
42 41
52 41
57 58
62 42
42 57
27 68
43 67
58 48
58 27
37 69
0
19
30
16
23
11
31
15
28
8
8
7
14
6
19
11
output:
2 14
2 8
-1 -1
2 11
1 164
*/
