poj3026Borg Maze（bfs+MST)

http://poj.org/problem?id=3026

BFS求出任意两个A或A和S的最短距离 然后最小生成树求和

把所有A和S存起来求BFS任意两点 搜超时了 之后改了改过了

View Code

  1 #include <iostream>

  2 #include<cstdio>

  3 #include<cstring>

  4 #include<algorithm>

  5 #include<queue>

  6 using namespace std;

  7 #define INF 0x3f3f3f

  8 struct node

  9 {

 10     int x,y,num;

 11 }al[110];

 12 char str[60][60];

 13 int f[60][60],dir[4][2]={0,1,0,-1,1,0,-1,0},n,m,w[110][110],visit[110],low[110],sum,ff[110][110];

 14 int judge(int i,int j)

 15 {

 16     if(i<1||i>n||j<1||j>m)

 17     return 0;

 18     if(str[i][j]=='#')

 19     return 0;

 20     return 1;

 21 }

 22 void bfs(int x,int y)

 23 {

 24     int i,j;

 25     queue<node>q;

 26     memset(f,0,sizeof(f));

 27     struct node st;

 28     st.x =x;

 29     st.y =y;

 30     f[st.x][st.y] = 1;

 31     st.num = 0;

 32     q.push(st);

 33     while(!q.empty())

 34     {

 35         struct node mt = q.front();

 36         int tx = mt.x;

 37         int ty = mt.y;

 38         int tnum = mt.num;

 39         q.pop();

 40         if(str[tx][ty]=='S'||str[tx][ty]=='A')

 41         {

 42             w[ff[x][y]][ff[tx][ty]] = tnum;

 43         }

 44         for(i = 0; i <= 3 ;i++)

 45         {

 46             int ti = dir[i][0]+tx;

 47             int tj = dir[i][1]+ty;

 48             if(!f[ti][tj]&&judge(ti,tj))

 49             {

 50                 f[ti][tj] = 1;

 51                 st.x = ti;

 52                 st.y = tj;

 53                 st.num = tnum+1;

 54                 q.push(st);

 55             }

 56         }

 57     }

 58 }

 59 void Prime(int n)

 60 {

 61      int i,j,k;

 62      memset(visit,0,sizeof(visit));

 63      visit[1] = 1;

 64      for(i = 2 ;i <= n ; i++)

 65          low[i] = w[1][i];

 66      for(i = 1 ; i <= n ; i++)

 67      {

 68          int max = INF;

 69          for(j = 1 ; j <= n ; j++)

 70              if(!visit[j]&&max>low[j])

 71                  max = low[k=j];

 72          if(max == INF)

 73              break;

 74          visit[k] = 1;

 75          sum+=max;

 76          for(j = 1 ; j <= n ; j++)

 77              if(!visit[j]&&low[j]>w[k][j])

 78              low[j] = w[k][j];

 79      }

 80 }

 81 int main()

 82 {

 83     int i,j,k,t,sx,sy;

 84     char ss[100];

 85     cin>>t;

 86     while(t--)

 87     {

 88         cin>>m>>n;

 89         gets(ss);

 90         memset(w,INF,sizeof(w));

 91         int g = 0;

 92         for(i = 1; i <= n ; i++)

 93         {

 94             getchar();

 95             for(j = 1; j <= m ; j++)

 96             {

 97                 scanf("%c",&str[i][j]);

 98                 if(str[i][j]=='A'||str[i][j]=='S')

 99                 {

100                     g++;

101                     ff[i][j]=g;

102                 }

103             }

104         }

105         int xx =0 ;

106         for(i = 1; i <= n ; i++)

107         for(j = 1 ; j <= m ; j++)

108            if(str[i][j]=='A'||str[i][j]=='S')

109                bfs(i,j);

110         sum = 0;

111         Prime(g);

112         cout<<sum<<endl;

113     }

114     return 0;

115 }