[Bzoj 1834] [Zjoi2010]network Network expansion (fee flow)

Description

Given a forward graph, each edge has a capacity of C and an expansion fee of W. The expansion fee here refers to the cost of expanding the capacity by 1. 1, in the case of no expansion, the maximum flow of 1 to N, 2, the maximum flow of 1 to n increases the minimum cost of expansion required by K.

Solution

Find out the maximum flow Maxflow first

For the minimum cost of expansion, for each edge, build a capacity of C cost of 0 of the edge, and build a capacity for the INF cost of the edge of W

The cost of running the flow of money into the Maxflow+k

#include <iostream>#include<cstdio>#include<queue>#include<cstdlib>#include<cstring>#defineINF 0x3f3f3f3fusing namespacestd;ints,t,n,m,k,head[1005],cnt=0, a[1005],dis[1005],pre[1005];intFlow,cost;BOOLinq[1005];intRead () {intx=0, f=1;CharC=GetChar ();  while(c<'0'|| C>'9'){        if(c=='-') f=-1; c=GetChar (); }     while(c>='0'&&c<='9') {x=x*Ten+c-'0'; c=GetChar (); }    returnx*F;}structnode{intNext from, To,cap,w;} edges[20005];voidAddedge (intUintVintCintW) {Edges[cnt].next=Head[u]; Head[u]=CNT; EDGES[CNT]. from=u; Edges[cnt].to=v; Edges[cnt].cap=C; EDGES[CNT].W=W; CNT++;}voidInsertintUintVintCintW)    {Addedge (u,v,c,w); Addedge (V,u,0,-W);} Queue<int>Q;voidMCMF (intx) {Flow=0, cost=0;  while(1) {memset (A,0,sizeof(a)); memset (DIS,0x3f,sizeof(DIS));        Q.push (s); Pre[s]=-1;d is[s]=0, a[s]=x?x-flow:inf,inq[s]=1;  while(!Q.empty ()) {            intu=Q.front (); Q.pop (), Inq[u]=0;  for(intI=head[u];~i;i=Edges[i].next) {                intv=edges[i].to; if(!x&&edges[i].cap==inf)Continue; if(dis[v]>dis[u]+edges[i].w&&edges[i].cap>0) {Dis[v]=dis[u]+EDGES[I].W; A[V]=min (a[u],edges[i].cap); PRE[V]=i; if(!inq[v]) {Q.push (v); inq[v]=1;} }            }        }        if(a[t]==0) Break; Flow+=A[t]; intp=T; Cost+=a[t]*Dis[t];  while(pre[p]!=-1) {Edges[pre[p]].cap-=A[t]; EDGES[PRE[P]^1].cap+=A[t]; P=EDGES[PRE[P]]. from; }    }}intMain () {memset (head,-1,sizeof(head)); N=read (), M=read (), k=read (); S=1, t=N;  for(intI=1; i<=m;i++)    {        intU=read (), V=read (), C=read (), w=read (); Insert (U,v,c,0);    Insert (U,V,INF,W); } MCMF (0); printf ("%d", Flow);    MCMF (k); printf ("%d\n", cost); return 0;}

[Bzoj 1834][zjoi2010]network Network expansion (charge flow)