ZOJ 2182 Cable TV Network (no-map cut-maximum flow)

Title Link: http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2182

Test instructions: Give an undirected graph, ask at least how many vertices to delete after the diagram becomes disconnected?

Idea: The original image of each point of the split (I,i+n), the edge of <i,i+n,1>, the edge of the original (U,V), The Edge <u+n,v,INF>,<v+n,u,INF>. The maximum flow (i+n,j) is then run for each pair of vertices (i,j). The minimum value for all the maximum flows is the answer.

struct node{int v,cap,next;};    Node Edges[n*10];int head[n],e;int curedge[n],h[n],num[n],pre[n];int s,t;void Add (int u,int v,int cap) {edges[e].v=v;    Edges[e].cap=cap;    Edges[e].next=head[u]; head[u]=e++;}    void Add (int u,int v,int cap) {Add (U,V,CAP); Add (v,u,0);}    int maxflow (int s,int t,int n) {clr (h,0); CLR (num,0);    int i;    FOR0 (i,n+1) curedge[i]=head[i];    int u=s,min,k,x,ans=0;            while (h[u]<n) {if (u==t) {min=inf*100;                for (I=S;I!=T;I=EDGES[CUREDGE[I]].V) {x=curedge[i];                    if (edges[x].cap<min) {min=edges[x].cap;                K=i; }} ans+=min;            U=k;                for (I=S;I!=T;I=EDGES[CUREDGE[I]].V) {x=curedge[i];                Edges[x].cap-=min;            Edges[x^1].cap+=min; }} for (I=curedge[u];i!=-1;i=edges[i].next) {if (edges[i].cap>0&&h[u]==h[edges[i].v]+1) {break;            }} if (I!=-1) {curedge[u]=i;            Pre[edges[i].v]=u;        U=EDGES[I].V;            } else {if (--num[h[u]]==0) break;            Curedge[u]=head[u];            X=n;                for (I=head[u];i!=-1;i=edges[i].next) {k=edges[i].v;            if (edges[i].cap>0&&h[k]<x) x=h[k]; } h[u]=x+1;            num[x+1]++;        if (u!=s) u=pre[u]; }} return ans;    int N,m;int a[55][55];int visit[55];void DFS (int u) {visit[u]=1;    int i,v;    FOR1 (I,n) if (A[u][i]&&!visit[i]) {DFS (i);    }}int OK () {clr (visit,0);    DFS (1);    int i;    FOR1 (I,n) if (!visit[i]) return 0; return 1;}    int cal (int s,int t) {clr (head,-1); e=0;    int i,j;    FOR1 (i,n) Add (i,i+n,1);    FOR1 (I,n) for (j=1;j<=n;j++) if (A[i][j]) {ADD (i+n,j,inf); } returnMaxflow (s+n,t,n+n+2);}    int get () {int x=0;    Char C=getchar ();    while (!isdigit (c)) C=getchar ();        while (IsDigit (c)) {x=x*10+c-' 0 ';    C=getchar (); } return x;}            int main () {while (scanf ("%d%d", &n,&m)!=-1) {if (m==0) {if (n==0) puts ("0");            else if (n==1) puts ("1");            Else puts ("0");        Continue        } CLR (a,0);        int u,v,i;            FOR0 (i,m) {u=get (); V=get ();        A[u+1][v+1]=a[v+1][u+1]=1;            } if (!ok ()) {puts ("0");        Continue        } Int J;        int ans=inf;            FOR1 (I,n) for (j=1;j<=n;j++) if (i!=j) {int x=cal (I,J);        Ans=min (ANS,X); } if (ans==inf| |        ans==n-1) Ans=n;    PR (ANS); }}