Bzoj3397: [usaco 2009 Feb] surround the islands ring island fence

3397: [usaco 2009 Feb] surround the islands fence time limit: 3 sec memory limit: 128 MB
Submit: 11 solved: 7
[Submit] [Status] Description John buys real estate in the Caribbean and prepares to raise cows on several islands. so he wants to fence all the islands. each island is a polygon. he walks in one direction along a boundary of the island and sometimes ships to another island. he can repair the fence from any polygon vertex. At any vertex that arrives, he can take a boat to a certain vertex of another island, but after repairing the fence of that island, he must return the island vertices from the original path immediately. there is a broken line between any two vertices, and each route requires a certain amount of fee. please help John calculate the minimum cost and let him finish all the fences. input N (3 ≤ n ≤ 1st) in the input 500 line, indicating the number of all island polygon. in the next n rows, enter two integers V1 and V2 (1 ≤ V1 ≤ n; 1 ≤ V2 ≤ n) to represent the two endpoints of a line segment that constitutes an island. next, enter a matrix of N rows and n columns, which indicates the cost of sailing between two vertices. output is an integer with the minimum cost. sample input12
1 7
7 3
3 6
6 10
10 1
2 12
2 9
8 9
8 12
11 5
5 4
11 4
0 15 9 20 25 8 10 13 17 8 8 7
15 0 12 12 10 10 8 15 8 8 9
9 12 0 25 20 18 16 14 13 7 12 12
20 12 25 0 8 13 14 15 10 10 10
25 10 20 8 0 16 20 18 17 9 11
8 10 18 13 16 0 10 9 11 10 8 12
10 8 16 14 20 10 0 18 20 6 16 15
13 15 14 15 18 9 18 0 5 12 12 13
17 15 13 15 17 11 20 5 0 22 8 10
8 8 7 10 18 10 6 12 22 0 11 12
8 8 12 10 9 8 16 12 8 11 0 9
7 9 12 10 11 12 15 13 10 12 9 0 sample output30hint

 

 

Source

Silver

Question: I understood the question for a while... And check the set to find all the polygon, and then mess with the + brute force code:

 1 #include<cstdio> 2 #include<cstdlib> 3 #include<cmath> 4 #include<cstring> 5 #include<algorithm> 6 #include<iostream> 7 #include<vector> 8 #include<map> 9 #include<set>10 #include<queue>11 #include<string>12 #define inf 100000000013 #define maxn 500+10014 #define maxm 500+10015 #define eps 1e-1016 #define ll long long17 #define pa pair<int,int>18 #define for0(i,n) for(int i=0;i<=(n);i++)19 #define for1(i,n) for(int i=1;i<=(n);i++)20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)22 #define mod 100000000723 using namespace std;24 inline int read()25 {26     int x=0,f=1;char ch=getchar();27     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}28     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}29     return x*f;30 }31 int n,tot,fa[maxn],p[maxn],f[maxn][maxn],a[maxn];32 bool v[maxn];33 inline int find(int x){return fa[x]==x?x:fa[x]=find(fa[x]);}34 int main()35 {36     freopen("input.txt","r",stdin);37     freopen("output.txt","w",stdout);38     n=read();39     for1(i,n)fa[i]=i;40     for1(i,n)41      {42          int x=find(read()),y=find(read());43          if(x!=y)fa[x]=y;44      }45     for1(i,n)46      {47       p[i]=find(i);48       if(v[p[i]])continue;49       v[p[i]]=1;50       a[++tot]=p[i];51      }52     memset(f,60,sizeof(f));53     for1(i,n) 54      for1(j,n)55       f[p[i]][p[j]]=min(f[p[i]][p[j]],read());56     int ans=inf;57     for1(i,tot)58      {59          int t=0;60          for1(j,tot) if(i!=j)t+=f[a[i]][a[j]];61          if(t<ans)ans=t;62      }63     printf("%d\n",ans<<1);     64     return 0;65 }

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Bzoj3397: [usaco 2009 Feb] surround the islands ring island fence