poj2195Going Home(最小费用最大流）

 

http://poj.org/problem?id=2195

模板题 超级源点-》men->house->超级汇点 坐标差值为两点的cost值 cap为1

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  1 #include <iostream>

  2 #include<cstdio>

  3 #include<cstring>

  4 #include<algorithm>

  5 #include<queue>

  6 #include<stdlib.h>

  7 #define INF 0xfffffff

  8 using namespace std;

  9 struct node

 10 {

 11     int u,v,next,cost,cap;

 12 }edge[210000];

 13 int men[1100][2],house[1100][2],head[1100],t,dist[1100],vis[1100],pp[1100];

 14 void init()

 15 {

 16     t = 0;

 17     memset(head,-1,sizeof(head));

 18 }

 19 void add(int u,int v,int c,int p)

 20 {

 21     edge[t].u = u;

 22     edge[t].v = v;

 23     edge[t].cap = c;

 24     edge[t].cost = p;

 25     edge[t].next = head[u];

 26     head[u] = t++;

 27     edge[t].v = u;

 28     edge[t].u = v;

 29     edge[t].cap = 0;

 30     edge[t].cost = -p;

 31     edge[t].next = head[v];

 32     head[v] = t++;

 33 }

 34 int spfa(int s,int en,int n)

 35 {

 36     int u,v,i;

 37     queue<int>q;

 38     memset(vis,0,sizeof(vis));

 39     memset(pp,-1,sizeof(pp));

 40     for(i = 0 ; i <= n ; i++)

 41     dist[i] = INF;

 42     dist[s] = 0;

 43     vis[s] = 1;

 44     q.push(s);

 45     while(!q.empty())

 46     {

 47         u = q.front();

 48         q.pop();

 49         vis[u] = 0;

 50         for(i = head[u] ; i != -1 ; i = edge[i].next)

 51         {

 52             v = edge[i].v;

 53             if(edge[i].cap&&dist[v]>dist[u]+edge[i].cost)

 54             {

 55                 dist[v] = dist[u]+edge[i].cost;

 56                 pp[v] = i;

 57                 if(!vis[v])

 58                 {

 59                     vis[v] = 1;

 60                     q.push(v);

 61                 }

 62             }

 63         }

 64     }

 65     if(dist[en]==INF)

 66     return 0;

 67     return 1;

 68 }

 69 int mcmf(int s,int en,int n)

 70 {

 71     int i,mc=0,minf;

 72     while(spfa(s,en,n))

 73     {

 74         minf = INF+1;

 75         for(i = pp[en] ; i != -1 ; i = pp[edge[i].u])

 76         if(minf>edge[i].cap)

 77         minf = edge[i].cap;

 78         for(i = pp[en]; i!=-1 ;i = pp[edge[i].u])

 79         {

 80             edge[i].cap-=minf;

 81             edge[i^1].cap+=minf;

 82         }

 83         mc+=minf*dist[en];

 84     }

 85     return mc;

 86 }

 87 int main()

 88 {

 89     int i,j,k,n,m,g,o;

 90     char c;

 91     while(cin>>n>>m)

 92     {

 93         if(n==0&&m==0)

 94             break;

 95         o=0;g=0;

 96         init();

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

 98         {

 99             getchar();

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

101             {

102                 scanf("%c",&c);

103                 if(c=='m')

104                 {

105                     g++;

106                     men[g][0] = i;

107                     men[g][1] = j;

108                 }

109                 if(c=='H')

110                 {

111                     o++;

112                     house[o][0] = i;

113                     house[o][1] = j;

114                 }

115             }

116         }

117         int s = 0 ,en = g+o+1;

118         for( i = 1 ; i <= g ; i++)

119         add(s,i,1,0);

120         for(i = 1 ; i <= o ;i++)

121         add(i+g,en,1,0);

122         for(i = 1 ; i <= g ; i++)

123             for(j = 1; j <= o ; j++)

124             {

125                 int x = abs(men[i][0]-house[j][0])+abs(men[i][1]-house[j][1]);

126                 add(i,g+j,1,x);

127             }

128         cout<<mcmf(s,en,g+o+1)<<endl;

129     }

130     return 0;

131 }