ISAP

跑的是比Dinic快辣。

更新：指针版。。。。

 #include<iostream>
 #include<cstdio>
 #include<cmath>
 #include<algorithm>
 #include<queue>
 #include<cstring>
 #define PAU putchar(' ')
 #define ENT putchar('\n')
 using namespace std;
 const int maxn=+,maxm=+,inf=-1u>>;
 struct ISAP{
     struct ted{int x,y,w;ted*nxt,*re;}adj[maxm],*fch[maxn],*cur[maxn],*ret[maxn],*ms;
     int gap[maxn],d[maxn],S,T,n;
     void init(int n){
         this->n=n;ms=adj;memset(d,-,sizeof(d));return;
     }
     void ade(int u,int v,int w){
         *ms=(ted){u,v,w,fch[u],ms+};fch[u]=ms++;
         *ms=(ted){v,u,,fch[v],ms-};fch[v]=ms++;
         return;
     }
     void bfs(){
         queue<int>Q;Q.push(T);d[T]=;
         while(!Q.empty()){
             int u=Q.front();Q.pop();
             for(ted*e=fch[u];e;e=e->nxt){
                 int v=e->y;if(d[v]<) d[v]=d[u]+,Q.push(v);
             }
         } return;
     }
     int flow(int S,int T){
         int k=S,flow=;ted*e;
         for(int i=;i<=n;i++) cur[i]=fch[i];
         while(d[S]<n){
             if(k==T){
                 int mi=inf;
                 for(int i=S;i!=T;i=cur[i]->y) if(cur[i]->w<mi) mi=cur[i]->w;
                 for(int i=S;i!=T;i=cur[i]->y) cur[i]->w-=mi,cur[i]->re->w+=mi;
                 flow+=mi;k=S;
             }
             for(e=cur[k];e;e=e->nxt) if(e->w>&&d[k]==d[e->y]+) break;
             if(e) cur[k]=e,ret[e->y]=e->re,k=e->y;
             else{
                 if(--gap[d[k]]==) break;cur[k]=fch[k];int lim=n;
                 for(ted*e=fch[k];e;e=e->nxt) if(e->w&&d[e->y]<lim) lim=d[e->y];
                 d[k]=lim+;gap[d[k]]++;if(k!=S) k=ret[k]->y;
             }
         } return flow;
     }
 }sol;
 inline int read(){
     int x=,sig=;char ch=getchar();
     while(!isdigit(ch)){if(ch=='-')sig=-;ch=getchar();}
     while(isdigit(ch))x=*x+ch-'',ch=getchar();
     return x*=sig;
 }
 inline void write(int x){
     if(x==){putchar('');return;}if(x<)putchar('-'),x=-x;
     int len=,buf[];while(x)buf[len++]=x%,x/=;
     for(int i=len-;i>=;i--)putchar(buf[i]+'');return;
 }
 int n,m;
 void init(){
     n=read();m=read();sol.init(n);
     int x,y,w;
     while(m--) x=read(),y=read(),w=read(),sol.ade(x,y,w);
     write(sol.flow(,n));
     return;
 }
 void work(){
     return;
 }
 void print(){
     return;
 }
 int main(){init();work();print();return ;}

数组版：

 #include<iostream>
 #include<cstdio>
 #include<cmath>
 #include<algorithm>
 #include<queue>
 #include<cstring>
 #define PAU putchar(' ')
 #define ENT putchar('\n')
 using namespace std;
 const int maxn=+,maxm=+,inf=-1u>>;
 struct ISAP{
     struct tedge{int x,y,w,next;}adj[maxm];int ms,fch[maxn];
     int gap[maxn],s[maxn],cur[maxn],d[maxn],S,T,top,n;
     void init(int n){
         this->n=n;ms=;top=;
         memset(fch,-,sizeof(fch));
         memset(d,-,sizeof(d));
         return;
     }
     void addedge(int w,int v,int u){
         adj[ms]=(tedge){u,v,w,fch[u]};fch[u]=ms++;
         adj[ms]=(tedge){v,u,,fch[v]};fch[v]=ms++;
         return;
     }
     void bfs(){
         queue<int>Q;Q.push(T);d[T]=;
         while(!Q.empty()){
             int u=Q.front();Q.pop();
             for(int i=fch[u];i!=-;i=adj[i].next){
                 int v=adj[i].y;
                 if(d[v]==-) d[v]=d[u]+,Q.push(v);
             }
         } return;
     }
     int maxflow(int S,int T){
         this->S=S;this->T=T;bfs();int k=S,i,flow=;
         for(i=;i<=n;i++) cur[i]=fch[i],gap[d[i]]++;
         while(d[S]<n){
             if(k==n){
                 int mi=inf,pos;
                 for(i=;i<top;i++) if(adj[s[i]].w<mi) mi=adj[s[i]].w,pos=i;
                 for(i=;i<top;i++) adj[s[i]].w-=mi,adj[s[i]^].w+=mi;
                 flow+=mi;top=pos;k=adj[s[top]].x;
             }
             for(i=cur[k];i!=-;i=adj[i].next){
                 int v=adj[i].y;
                 if(adj[i].w&&d[k]==d[v]+){cur[k]=i;k=v;s[top++]=i;break;}
             }
             if(i==-){
                 int lim=n;
                 for(i=fch[k];i!=-;i=adj[i].next){
                     int v=adj[i].y;
                     if(adj[i].w&&d[v]<lim) lim=d[v],cur[k]=i;
                 } if(--gap[d[k]]==) break;
                 d[k]=lim+;gap[d[k]]++;
                 if(k!=S) k=adj[s[--top]].x;
             }
         } return flow;
     }
 }sol;
 inline int read(){
     int x=,sig=;char ch=getchar();
     while(!isdigit(ch)){if(ch=='-') sig=-;ch=getchar();}
     while(isdigit(ch)) x=*x+ch-'',ch=getchar();
     return x*=sig;
 }
 inline void write(int x){
     if(x==){putchar('');return;}if(x<) putchar('-'),x=-x;
     int len=,buf[];while(x) buf[len++]=x%,x/=;
     for(int i=len-;i>=;i--) putchar(buf[i]+'');return;
 }
 void init(){
     int n=read(),m=read();sol.init(n);
     while(m--) sol.addedge(read(),read(),read());
     write(sol.maxflow(,n));
     return;
 }
 void work(){
     return;
 }
 void print(){
     return;
 }
 int main(){
     init();work();print();return ;
 }

搜索

复制