题目大概说有n个城市，由m条无向边相连，每条边每天最多运送cap桶酒且其运送一桶的花费是cost。现在从1号城市开始出发运酒，供应到2到n号城市，这些城市的收购单价是price，问最大的盈利是多少。
。。。顺路AC
1 #include 2 #include 3 #include 4 #include 5 using namespace std; 6 #define INF (1<<30) 7 #define MAXN 111 8 #define MAXM 111*222 9 struct Edge{10 int u,v,cap,cost,next;11 }edge[MAXM];12 int head[MAXN];13 int NV,NE,vs,vt;14 15 void addEdge(int u,int v,int cap,int cost){16 edge[NE].u=u; edge[NE].v=v; edge[NE].cap=cap; edge[NE].cost=cost;17 edge[NE].next=head[u]; head[u]=NE++;18 edge[NE].u=v; edge[NE].v=u; edge[NE].cap=0; edge[NE].cost=-cost;19 edge[NE].next=head[v]; head[v]=NE++;20 }21 bool vis[MAXN];22 int d[MAXN],pre[MAXN];23 bool SPFA(){24 for(int i=0;i
que;31 que.push(vs);32 while(!que.empty()){33 int u=que.front(); que.pop();34 for(int i=head[u]; i!=-1; i=edge[i].next){35 int v=edge[i].v;36 if(edge[i].cap && d[v]>d[u]+edge[i].cost){37 d[v]=d[u]+edge[i].cost;38 pre[v]=i;39 if(!vis[v]){40 vis[v]=1;41 que.push(v);42 }43 }44 }45 vis[u]=0;46 }47 return d[vt]!=INF;48 }49 int MCMF(){50 int res=0;51 while(SPFA()){52 int flow=INF,cost=0;53 for(int u=vt; u!=vs; u=edge[pre[u]].u){54 flow=min(flow,edge[pre[u]].cap);55 }56 for(int u=vt; u!=vs; u=edge[pre[u]].u){57 edge[pre[u]].cap-=flow;58 edge[pre[u]^1].cap+=flow;59 cost+=flow*edge[pre[u]].cost;60 }61 if(cost>=0) break;62 res+=cost;63 }64 return res;65 }66 int main(){67 int n,m,a,b,c,d;68 while(~scanf("%d%d",&n,&m)){69 vs=1; vt=n+1; NV=vt+1; NE=0;70 memset(head,-1,sizeof(head));71 for(int i=2; i<=n; ++i){72 scanf("%d",&a);73 addEdge(i,vt,INF,-a);74 }75 while(m--){76 scanf("%d%d%d%d",&a,&b,&c,&d);77 addEdge(a,b,c,d);78 addEdge(b,a,c,d);79 }80 printf("%d\n",-MCMF());81 }82 return 0;83 }