ZKW费用流修正

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<algorithm>
 5 #include<stack>
 6 #include<queue>
 7 #include<cstring>
 8 #define PAU putchar(‘ ‘)
 9 #define ENT putchar(‘\n‘)
10 #define MSE(a,b) memset(a,b,sizeof(a))
11 #define REN(x) for(ted*e=fch[x];e;e=e->nxt)
12 #define TIL(x) for(int i=1;i<=x;i++)
13 using namespace std;
14 const int maxn=2000+10,maxm=20000+10,inf=1e9;
15 struct zkw{
16     struct ted{int x,y,w,c;ted*nxt,*re;}adj[maxm],*fch[maxn],*ms;
17     int n,S,T,d[maxn],cost,ans;bool inq[maxn],vis[maxn];
18     void init(int n){this->n=n;ms=adj;MSE(vis,false);MSE(inq,false);return;}
19     void add(int x,int y,int w,int c){
20         *ms=(ted){x,y,w,c,fch[x],ms+1};fch[x]=ms++;
21         *ms=(ted){y,x,0,-c,fch[y],ms-1};fch[y]=ms++;
22         return;
23     }
24     bool bfs(){
25         TIL(n)d[i]=inf;queue<int>Q;Q.push(T);d[T]=0;
26         while(!Q.empty()){
27             int x=Q.front();Q.pop();inq[x]=false;REN(x){
28                 int v=e->y;if(e->re->w&&d[v]>d[x]+e->re->c){
29                     d[v]=d[x]+e->re->c;if(!inq[v])inq[v]=true,Q.push(v);
30                 }
31             }
32         }for(ted*e=adj;e!=ms;e++)e->c+=d[e->y]-d[e->x];cost+=d[S];return d[S]!=inf;
33     }
34     int dfs(int x,int aug){
35         if(x==T||!aug)return(ans+=aug*cost,aug);int flow=0,k;vis[x]=true;REN(x){
36             int v=e->y;if(e->w&&!e->c&&!vis[v]&&(k=dfs(v,min(aug,e->w)))){
37                 e->w-=k;e->re->w+=k;flow+=k;aug-=k;if(!aug)break;
38             }
39         }return flow;
40     }
41     int mcmf(int S,int T){
42         this->S=S;this->T=T;while(bfs())do MSE(vis,false);while(dfs(S,inf));return ans;
43     }
44 }sol;
45 inline int read(){
46     int x=0,sig=1;char ch=getchar();
47     for(;!isdigit(ch);ch=getchar())if(ch==‘-‘)sig=0;
48     for(;isdigit(ch);ch=getchar())x=10*x+ch-‘0‘;
49     return sig?x:-x;
50 }
51 inline void write(int x){
52     if(x==0){putchar(‘0‘);return;}if(x<0)putchar(‘-‘),x=-x;
53     int len=0,buf[15];while(x)buf[len++]=x%10,x/=10;
54     for(int i=len-1;i>=0;i--)putchar(buf[i]+‘0‘);return;
55 }
56 int n,m;
57 int main(){
58     n=read();m=read();sol.init(n);int x,y,w;
59     TIL(m)x=read(),y=read(),w=read(),sol.add(x,y,w,read());write(sol.mcmf(1,n));
60     return 0;
61 }