loj 101 最大流

冬令营送到我脸上的20分都没拿全

心态爆炸

冬令营前一天学的dinic

后一天才发出来

 #include<iostream>
 #include<cstdio>
 #include<cmath>
 #include<cstdlib>
 #include<cstring>
 #include<algorithm>
 #include<vector>
 #include<queue>
 #define inf 2139062143
 #define ll long long
 #define MAXN 1000100
 using namespace std;
 inline int read()
 {
     int x=,f=;char ch=getchar();
     while(!isdigit(ch)) {if(ch=='-') f=-;ch=getchar();}
     while(isdigit(ch)) {x=x*+ch-'';ch=getchar();}
     return x*f;
 }
 struct Dinic
 {
     int fst[MAXN],nxt[MAXN<<],to[MAXN<<],val[MAXN<<],cnt,n,m,s,t;
     Dinic() {cnt=;memset(fst,0xff,sizeof(fst));}
     void add(int u,int v,int w) {nxt[cnt]=fst[u],fst[u]=cnt,to[cnt]=v,val[cnt++]=w;}
     int q[MAXN],dep[MAXN],cur[MAXN],vis[MAXN],tot;
     int BFS()
     {
         int l=,r=;
         memset(dep,0xff,sizeof(dep));
         vis[t]=++tot,q[++r]=t;
         while(l<=r)
         {
             int x=q[l++];cur[x]=fst[x];
             for(int i=fst[x];i!=-;i=nxt[i])
             {
                 if(val[i^]&&vis[to[i]]!=tot)
                 {
                     vis[to[i]]=tot,dep[to[i]]=dep[x]+,q[++r]=to[i];
                     if(to[i]==s) return ;
                 }
             }
         }
         return vis[s]==tot;
     }
     int DFS(int x,int a)
     {
         if(x==t||!a) return a;
         int flow=,f;
         for(int& i=cur[x];i!=-;i=nxt[i])
         {
             if(val[i]&&dep[to[i]]==dep[x]-&&(f=DFS(to[i],min(a,val[i]))))
             {
                 val[i]-=f,val[i^]+=f,flow+=f,a-=f;
                 if(!a) break;
             }
         }
         return flow;
     }
     ll solve()
     {
         ll ans=;int f;
         while(BFS())
         {
             memcpy(cur,fst,sizeof(cur));
             while(f=DFS(s,inf)) ans+=f;
         }
         return ans;
     }
 }D;
 int main()
 {
     int k;
     D.n=read(),k=D.m=read(),D.s=read(),D.t=read();
     int u,v,w;
     for(int i=;i<=k;i++) {u=read(),v=read(),w=read();D.add(u,v,w);D.add(v,u,);}
     printf("%lld",D.solve());
 }