"POJ 1459 Power Network"

It is not understandable that the 0ms on the evaluation station is how to get out.

The problem became gentler and cuter after the creation of the super-source and super-meeting points. In fact, it is gentle and lovely. Compare what you can find:

(1) Aidemont Kap algorithm (2) Dinnick algorithm (3) Improved version Aidemont Kap algorithm (MY method)

Not to tube that 0ms, then (3) algorithm is the most wonderful "its alias is: ISAP", time objective.

This is even a ISAP template bar (in addition to the input of the ugly few lines, the rest are standard rice cake template!) ）

  1  #include <stdio.h> 2  # Include<algorithm> 3  #include <queue>  4  #include <cstring> 5   #define  Go (i,a,b) for (int i=a;i<=b;i++)  6   #define  FO (i,a,x) for (int i=a[x],v=e[i].v;i>-1;i=e[i].next,v=e[i].v)  7   #define  Mem (A, B) memset (A,b,sizeof (a))  8  using   namespace  std; const  int  N=5000  ; 9 struct e{int v,next,flow,cap;} e[n* N]; 0  int n,n_power,n_user,m,s,t,head[n],k= , d[n];  int  num[n],cur[n],pree[n],pren[n];   void ADD (int u,int v,int flow,int cap) {E[k ]= (E) {v,head[u],flow,cap};head[u]=k++;}  void  BFS ()  { queue<int>q;  BOOL vis[n]={0};q.push (T);d [t]=0 ;  -  while (!  q.empty ())   - {u=int  Q.front (); Q.pop (); Fo (i,head,u)if(!e[i].cap&&!   Vis[v]) vis[v]=1, d[v]=d[u]+1   , Q.push (v);    + }  } u,a= int ()} () {int '2147483645 ;  u=t;  while (u!=s) {int i=pree[u];a=min (a,e[i].cap-e[i].flow); u= pren[u];}  u=t;  while (u!=s) {int i=pree[u];e[i].flow+=a;e[i^1].flow-=a;u=pren[u];} return  A;}  the int main () {while (~scanf ("%d%d%d%d", &n, &n_power,&n_user,& m))   - {   s=0; t=n+1; Char _;mem (head,-1 );  Go (i,1, m) {int u,v,cap;scanf ("  %c%d%c%d%c%d", &_,&u,&_,&v,&_,& cap);  u++,v++; ADD (U,v,0, CAP); ADD (V,u,0,0 );}  to go (i,1, n_power) {int v,cap;scanf ("  %c%d%c%d", &_,&v,&_,& cap);  v++; ADD (S,v,0, CAP); ADD (V,s,0,0 );}  Go (i,1, n_user) {int u,cap;scanf ("  %c%d%c%d", &_,&u ,&_,& cap);  u++; ADD (U,t,0, CAP); ADD (T,u,0,0);} BFS (); Mem (num,0 );  * n+ Go (i,0,1) num[d[i]]++,cur[i]=   Head[i]; Panax Notoginseng int u=s,flow=0 ;  -  while (d[s]<t+1  )  { U==t?flow+=aug (), U=s:1;  BOOL retreat=1 ; (i,cur,u)  if(e[i].cap>e[i].flow&&d[u]==d[v]+1  ) (retreat=0; cur[u]=pree[v]=i;pren[v]=u;u=v;   Break;}  if(!retreat)continue ;  $  $ int Min=t;fo (i,head,u) {if(e[i].cap>e[i].flow) min=  min (min,d[v]);}  - if (! (--num[d[u])) break; num[d[u]=min+1]++  ;  cur[u]=head[u];u==s? 1: u= Pren[u];   the } printf ("%d\n"  , flow);  { 0}return ;} // Paul_guderian 

"Improved version Aidemont KAP algorithm"

Network Flow Two learning points: learn to transform the problem, learn a few models? Are you questioning the authority of the magic rice pie? Then I'll give you a rice cake!

Zbh not to play with Isaac's union ... I wrote this blog to express my anger!

"POJ 1459 Power Network"