模板 最小费用最大流
洛谷P3381 【模板】最小费用最大流
这题我用这个会T 只有 80分，感觉最小费用最大流就应该加一些常数优化，否则会非常慢
1 #include <cstdio> 2 #include <cmath> 3 #include <cstdlib> 4 #include <cstring> 5 #include <string> 6 #include <algorithm> 7 #include <iostream> 8 #include <iomanip> 9 #include <queue> 10 #define inf 1e9 11 #define maxn 5005 12 #define maxm 50005 13 #define PAIR pair <int,int> 14 using namespace std ; 15 16 int n,m,s,t,x,y,vol,cost,gEdgeCount ; 17 18 PAIR ans ; 19 20 struct Edge{ 21 int to,vol,cost,next ; 22 }; 23 Edge gEdges[2*maxm] ; 24 25 int gHead[maxn],gPre[maxn],gPath[maxn],gDist[maxn] ; 26 27 inline void InsertEdge(int u,int v,int vol,int cost) 28 { 29 gEdges[gEdgeCount].to = v ; 30 gEdges[gEdgeCount].vol = vol ; 31 gEdges[gEdgeCount].cost = cost ; 32 gEdges[gEdgeCount].next = gHead[u] ; 33 gHead[u] = gEdgeCount++ ; 34 35 gEdges[gEdgeCount].to = u ; 36 gEdges[gEdgeCount].vol = 0 ; 37 gEdges[gEdgeCount].cost = -cost ; // 取反 是为了之后能够退流 38 gEdges[gEdgeCount].next = gHead[v] ; 39 gHead[v] = gEdgeCount++ ; 40 } 41 42 inline bool Spfa( int s,int t ) 43 { 44 for(int i=0;i<=n;i++) gPre[ i ] = -1 ; 45 for(int i=0;i<=n;i++) gDist[ i ] = 1e9 ; 46 gDist[ s ] = 0 ; 47 queue<int> Q ; 48 Q.push(s) ; 49 while(!Q.empty()) 50 { 51 int u = Q.front() ; 52 Q.pop() ; 53 54 for(int e = gHead[u];e != -1 ;e = gEdges[e].next ) 55 { 56 int v = gEdges[e].to ; 57 if(gEdges[e].vol>0&&gDist[u] + gEdges[e].cost < gDist[v]) 58 { 59 gDist[v] = gDist[u] + gEdges[e].cost ; 60 gPre[v] = u ; 61 gPath[v] = e ; 62 Q.push(v) ; 63 } 64 } 65 } 66 if(gPre[t]==-1) 67 return false ; 68 return true ; 69 } 70 71 inline PAIR MinCostFlow(int s,int t) 72 { 73 int cost = 0,flow = 0 ; 74 while(Spfa(s,t)) 75 { 76 int f = inf ; 77 for(int u = t; u != s; u = gPre[u] ) 78 if(gEdges[gPath[u]].vol < f ) 79 f = gEdges[gPath[u]].vol ; 80 flow+=f ; 81 cost+= gDist[t] * f ; 82 for(int u=t;u!=s;u=gPre[u] ) 83 { 84 gEdges[gPath[u]].vol-=f ; 85 gEdges[gPath[u]^1].vol+=f ; 86 } 87 } 88 PAIR ans ; 89 ans.first = flow ; ans.second = cost ; 90 return ans ; 91 } 92 93 int main() 94 { 95 scanf("%d%d%d%d",&n,&m,&s,&t) ; 96 for(int i=0;i<=n;i++) gHead[ i ] = -1 ; 97 for(int i=1;i<=m;i++) 98 { 99 scanf("%d%d%d%d",&x,&y,&vol,&cost) ; 100 InsertEdge(x,y,vol,cost) ; 101 } 102 ans = MinCostFlow(s,t) ; 103 printf("%d %d ",ans.first,ans.second ) ; 104 return 0 ; 105 }
这个加了一下优化
然后就跑得比较快了 1400ms
1 #include<cstdio> 2 #include<cstring> 3 const int maxn=1e4+10; 4 const int maxm=1e5+10; 5 const int maxt=2139062143; 6 inline int min_(int x,int y){return x<y?x:y;} 7 int n,m,s,t,nflow,nfee,flow,fee; 8 int a,b,c,d; 9 int h[maxn],hs=1; 10 int e_q[maxm],e_z[maxm],e_n[maxm],e_w[maxm],e_f[maxm]; 11 int add(int q,int z,int k,int w,int f){e_q[k]=q,e_z[k]=z,e_n[k]=h[q],e_w[k]=w,e_f[k]=f,h[q]=k;} 12 int q[maxm],head,tail; 13 int w[maxn],p[maxn]; 14 bool v[maxn]; 15 int ap(int k,int v){ 16 if(k==s) return v; 17 int ret=ap(e_q[p[k]],min_(v,e_w[p[k]])); 18 if(!e_f[p[k]^1]) add(k,e_q[p[k]],p[k]^1,0,-e_f[p[k]]); 19 e_w[p[k]]-=ret,e_w[p[k]^1]+=ret; 20 return ret; 21 } 22 void Mcmf(){ 23 while(1){ 24 memset(w,0x7f,sizeof(w)); 25 memset(v,0,sizeof(v)); 26 head=tail=w[s]=0; 27 q[head++]=s,v[s]=1; 28 while(head>tail){ 29 a=q[tail++],v[a]=0; 30 for(int i=h[a];i;i=e_n[i]) 31 if(0ll+e_f[i]+w[a]<w[e_z[i]]&&e_w[i]){ 32 p[e_z[i]]=i; 33 w[e_z[i]]=e_f[i]+w[a]; 34 if(!v[e_z[i]]) q[head++]=e_z[i],v[e_z[i]]=1; 35 } 36 } 37 if(w[t]==maxt) break; 38 nflow=ap(t,maxt); 39 flow+=nflow; 40 fee+=nflow*w[t]; 41 } 42 } 43 int main(){ 44 scanf("%d%d%d%d",&n,&m,&s,&t); 45 for(int i=1;i<=m;i++){ 46 scanf("%d%d%d%d",&a,&b,&c,&d); 47 ++hs,add(a,b,hs,c,d),hs++; 48 } 49 Mcmf(); 50 printf("%d %d ",flow,fee); 51 return 0; 52 }