Poj 2125 "min cut"

Topic: A direction-free graph, the cost of deleting a point of all the < Span class= "Mrow" id= "mathjax-span-2" > a i Span style= "Display:inline-block; width:0px; Height:2.279em; " > , the cost of removing all the edges of a point is < Span class= "Mrow" id= "mathjax-span-7" > b i Span style= "Display:inline-block; width:0px; Height:2.279em; " > To remove the minimum cost of all edges

Split a point I into two points i,i '
Build diagram:
S-I, Flow < Span class= "Mrow" id= "mathjax-span-12" > b i Span style= "Display:inline-block; width:0px; Height:2.279em; " >
I-j ', Flow inf
I ' T, flow a i
Then run the minimum cut Qaq

If it is a table, you can also split it into columns like this ...

If the requirement is the minimum number of times, you can precede the weights with a large number ...

#include <iostream>#include <algorithm>#include <cstring>#include <string>#include <ctime>#include <cmath>#include <cstdlib>#include <cstdio>#define N 2005#define M 50005#define INF 1000000000using namespace STD;intn,m,siz=1, s,t;intFIRST[N],NEXT[M],TO[M],LEN[M];intD[n],p[n],c[n],r[n],v[n];voidInser (intXintYintW) {next[++siz]=first[x];    First[x]=siz;    To[siz]=y; Len[siz]=w;}voidAdd_edge (intXintYintW) {Inser (x,y,w), Inser (Y,x,0);}BOOLBFS () {intHead=0, tail=1;memset(d,0,sizeof(d)); d[p[1]=s]=1; while(Head^tail) {intX=p[++head]; for(intI=first[x];i;i=next[i])if(!d[to[i]]&&len[i]) d[p[++tail]=to[i]]=d[x]+1; }returnD[T];}intDfsintXintFlow) {if(x==t)returnFlowintret=0; for(intI=first[x];i&&flow;i=next[i])if(d[to[i]]==d[x]+1&&len[i]) {intW=dfs (To[i],min (flow,len[i));            Len[i]-=w; len[i^1]+=w;            Ret+=w;        Flow-=w; }if(!ret) d[x]=0;returnRET;}intDinic () {intret=0; while(BFS ())) Ret+=dfs (S,inf);returnRET;}voidDFS (intx) {v[x]=true; for(intI=first[x];i;i=next[i])if(!v[to[i]]&&len[i]) DFS (To[i]);}intMain () {scanf("%d%d", &n,&m); s=n<<1|1, t=s+1; for(intX,i=1; i<=n;i++)scanf("%d", &x), Add_edge (i+n,t,x); for(intX,i=1; i<=n;i++)scanf("%d", &x), Add_edge (s,i,x); for(intX,y,i=1; i<=m;i++) {scanf("%d%d", &x,&y);    Add_edge (X,y+n,inf); }printf("%d\n", Dinic ());inttot=0; DFS (S); for(intI=1; i<=n;i++) {if(!v[i]) r[i]=1, tot++;if(V[i+n]) c[i]=1, tot++; }printf("%d\n", tot); for(intI=1; i<=n;i++) {if(R[i])printf("%d-\n", i);if(C[i])printf("%d +\n", i); }return 0;}

Poj 2125 "min cut"