BZOJ 3130 Sdoi2013 费用流

 1 #include <bits/stdc++.h>
 2 #define ll long long 
 3 #define eps 1e-5
 4 using namespace std;
 5 inline int read(){
 6     int x=0;int f=1;char ch=getchar();
 7     while(!isdigit(ch)) {if(ch==‘-‘) f=-1;ch=getchar();}
 8     while(isdigit(ch)) {x=x*10+ch-‘0‘;ch=getchar();}
 9     return x*f;
10 }
11 const int MAXN=2e3+10;
12 struct node{
13     int x,y,next,back;
14     double flow;
15 }e[MAXN<<1],s[MAXN];
16 int linkk[MAXN<<1],level[MAXN],len=0,n,m,p;
17 inline void insert(int xx,int yy,double f){
18     e[++len].y=yy;e[len].next=linkk[xx];linkk[xx]=len;e[len].flow=f;e[len].back=len+1;
19     e[++len].y=xx;e[len].next=linkk[yy];linkk[yy]=len;e[len].flow=0;e[len].back=len-1;
20 }
21 inline void build(double num){
22     memset(linkk,0,sizeof(linkk));
23     len=0;
24     for(int i=1;i<=m;i++){
25         insert(s[i].x,s[i].y,min(num,s[i].flow));
26     }
27 }
28 void init(){
29     n=read();m=read();p=read();
30     for(int i=1;i<=m;i++){
31         s[i].x=read();s[i].y=read();s[i].flow=read();
32     }
33     build(23712837);
34 }
35 int q[MAXN<<4],head,tail;
36 inline bool getlevel(){
37     memset(level,-1,sizeof(level));
38     head=tail=0;
39     q[++tail]=1;
40     level[1]=0;
41     while(head<tail){
42         int tn=q[++head];
43         for(int i=linkk[tn];i;i=e[i].next){
44             if(level[e[i].y]==-1&&e[i].flow){
45                 level[e[i].y]=level[tn]+1;
46                 q[++tail]=e[i].y;
47             }
48         }
49     }
50     return level[n]>=0;
51 }
52 inline double getmaxflow(int st,double flow){
53     if(st==n) return flow;
54     double maxflow=0;double d=0;
55     for(int i=linkk[st];i&&maxflow<flow;i=e[i].next){
56         if(level[e[i].y]==level[st]+1&&e[i].flow>0){
57             if(d=getmaxflow(e[i].y,min(flow-maxflow,e[i].flow))){
58                 e[i].flow-=d;
59                 e[e[i].back].flow+=d;
60                 maxflow+=d;
61             }
62         }
63     }
64     if(!maxflow) level[st]=-1;
65     return maxflow;
66 }
67 inline double dinic(){
68     double sum=0;double ans;
69     while(getlevel()){
70         while(ans=getmaxflow(1,312323233)){
71             sum+=ans;
72         }
73     }
74     return sum;
75 }
76 int main(){
77     //freopen("All.in","r",stdin);
78     //freopen("zhang.out","w",stdout);
79     init();
80     double k=dinic();
81     cout<<k<<endl;
82     double l=0;double r=0;
83     for(int i=1;i<=m;i++){
84         r=max(r,s[i].flow);
85     }
86     while((r-l)>eps){
87         //printf("%lf %lf\n",l,r);
88         double mid=(l+r)*0.5;
89         build(mid);
90         double t=dinic();
91         if(abs(t-k)<eps) r=mid;
92         else l=mid;
93     }
94     printf("%.4f\n",l*p);
95     return 0;
96 }

 1 #include <bits/stdc++.h>
 2 #define ll long long
 3 using namespace std;
 4 inline ll read(){
 5     ll x=0;ll f=1;char ch=getchar();
 6     while(!isdigit(ch)) {if(ch==‘-‘) f=-1;ch=getchar();}
 7     while(isdigit(ch)) {x=x*10+ch-‘0‘;ch=getchar();}
 8     return x*f;
 9 }
10 int main(){
11     srand(time(int(NULL)));
12     freopen("All.in","w",stdout);
13     int n=rand()%107+1;int m=rand()%1007+n;int T=rand()%57;
14     cout<<n<<‘ ‘<<m<<‘ ‘<<T<<endl;
15     cout<<rand()%n+1<<‘ ‘<<rand()%m+1<<‘ ‘<<T<<endl;
16     for(int i=1;i<=m;i++){
17         int xx=rand()%n+1;
18         int yy=rand()%n+1;
19         int vv=rand()%107;
20         printf("%d %d %d\n",xx,yy,vv);
21     }
22     return 0;
23 }