hdu 3435 A new Graph Game

http://acm.hdu.edu.cn/showproblem.php?pid=3435

  1 #include <cstdio>

  2 #include <iostream>

  3 #include <cstring>

  4 #include <queue>

  5 #include <algorithm>

  6 #define inf 0x3f3f3f3f

  7 #define maxn 54444

  8 using namespace std;

  9 

 10 queue<int>q;

 11 struct node

 12 {

 13     int u,v,next,val,f;

 14 } p[maxn];

 15 int head[maxn];

 16 bool vis[maxn];

 17 int dis[maxn];

 18 int pre[maxn];

 19 int n,m,s,t,e;

 20 

 21 void add(int u,int v,int f,int c)

 22 {

 23     p[e].u=u;

 24     p[e].v=v;

 25     p[e].f=f;

 26     p[e].val=c;

 27     p[e].next=head[u];

 28     head[u]=e++;

 29     p[e].u=v;

 30     p[e].v=u;

 31     p[e].f=0;

 32     p[e].val=-c;

 33     p[e].next=head[v];

 34     head[v]=e++;

 35 

 36 }

 37 

 38 bool spfa()

 39 {

 40     int j,k,i;

 41     while(!q.empty()) q.pop();

 42     memset(vis,false,sizeof(vis));

 43     memset(dis,0x3f,sizeof(dis));

 44     memset(pre,-1,sizeof(pre));

 45     vis[s]=true;

 46     dis[s]=0;

 47     q.push(s);

 48     while(!q.empty())

 49     {

 50         int u=q.front();

 51         q.pop();

 52         vis[u]=false;

 53         for(j=head[u]; j!=-1; j=p[j].next)

 54         {

 55             int v=p[j].v;

 56             if(p[j].f&&dis[u]+p[j].val<dis[v])

 57             {

 58                 dis[v]=dis[u]+p[j].val;

 59                 pre[v]=j;

 60                 if(!vis[v])

 61                 {

 62                     vis[v]=true;

 63                     q.push(v);

 64                 }

 65             }

 66         }

 67     }

 68     return dis[t]!=inf;

 69 }

 70 

 71 

 72 int mincost()

 73 {

 74     int ret=0,u;

 75     while(spfa())

 76     {

 77         u=pre[t];

 78         ret+=dis[t];

 79         while(u!=-1)

 80         {

 81             p[u].f--;

 82             p[u^1].f++;

 83             u=pre[p[u].u];

 84         }

 85     }

 86     return ret;

 87 }

 88 int main()

 89 {

 90     int case1;

 91     scanf("%d",&case1);

 92     for(int k=1; k<=case1; k++)

 93     {

 94         e=0;

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

 96         scanf("%d%d",&n,&m);

 97         s=0;

 98         t=2*n+1;

 99         for(int i=1; i<=m; i++)

100         {

101             int a,b,c;

102             scanf("%d%d%d",&a,&b,&c);

103             add(a,b+n,1,c);

104             add(b,a+n,1,c);

105         }

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

107         {

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

109             add(i+n,t,1,0);

110         }

111         int j;

112         int ans=mincost();

113         for(j=head[s]; j!=-1; j=p[j].next)

114          if(p[j].f!=0) break;

115         if(j==-1) printf("Case %d: %d\n",k,ans);

116         else printf("Case %d: NO\n",k);

117     }

118     return 0;

119 }

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