nbu 2429 Transfer stations(二)
;
for(int i=g[u];i!=-1;i=edg[i].next){
edge& e=edg[i],ee=edg[i^1];
if(dis[e.to]==-1 && ee.flow>0){
gap[dis[e.to]=dis[u]+1]++;
q[++tail]=e.to;
}
}
}
return dis[s]!=-1;
}
type maxFlow(int s,int t){
if(!bfs(s,t)) return 0;
type res=0,a;
int i;
for(i=0;i
pre[s]=s,cur[s]=g[s],cur[t]=g[t];
for(int u=s;dis[s]
if(u==t){
for(a=-1;u!=s;u=pre[u])
getmin(a,edg[cur[pre[u]]].flow);
for(u=t;u!=s;u=pre[u]){
edg[cur[pre[u]]].flow-=a;
edg[cur[pre[u]]^1].flow+=a;
}
res+=a;
}
bool ok=0;
for(i=cur[u];i!=-1;i=edg[i].next){
edge& e=edg[i];
if(dis[u]==dis[e.to]+1 && e.flow>0){
cur[u]=i,pre[e.to]=u,u=e.to;
ok=1;break;
}
}
if(ok) continue;
int mindis=n-1;
for(i=g[u];i!=-1;i=edg[i].next){
edge& e=edg[i];
if(mindis>dis[e.to] && e.flow>0)
mindis=dis[e.to],cur[u]=i;
}
if(--gap[dis[u]]==0) break;
gap[dis[u]=mindis+1]++,u=pre[u];
}
return res;
}
}p;
void run(){
int i,j;
p.init(n+m+2);
int tot=0;
for(i=1;i<=n;i++){
scanf("%d",&j);
p.insert(i,n+m+1,j);
}
for(i=1;i<=m;i++){
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
p.insert(0,n+i,c);
p.insert(n+i,a,INF);
p.insert(n+i,b,INF);
tot+=c;
}
printf("%d\n",tot-p.maxFlow(0,n+m+1));
}
void preSof(){
}
int main(){
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
preSof();
//run();
while(~scanf("%d%d",&n,&m)) run();
//for(scanf("%d",&TS);cas<=TS;cas++) run();
return 0;
}
代码(二):
[cpp]
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
using namespace std;
#define ll long long
#define ls rt<<1
#define rs ls|1
#define lson l,mid,ls
#define rson mid+1,r,rs
#define middle (l+r)>>1
#define eps (1e-8)
#define clr_all(x,c) memset(x,c,sizeof(x))
#define clr(x,c,n) memset(x,c,sizeof(x[0])*(n+1))
#define MOD 1000000009
#define INF 0x3f3f3f3f
#define PI acos(-1.0)
#define _max(x,y) (((x)>(y)) (x):(y))
#define _min(x,y) (((x)<(y)) (x):(y))
#define _abs(x) ((x)<0 (-(x)):(x))
#define getmin(x,y) (x= ((x)<0 || (y)<(x)) (y):(x))
#define getmax(x,y) (x= ((y)>(x)) (y):(x))
template void _swap(T &x,T &y){T t=x;x=y;y=t;}
int TS,cas=1;
const int M=5000+5;
int n,m,U;
int pr[M],d[M];
int a[M*10],b[M*10],c[M*10];
struct sap{
typedef int type;
struct edge{
int to,next;
type flow;
}edg[999999];
int n,m;
int g[M],cur[M],pre[M];
int dis[M],gap[M];
int q[M],head,tail;
void init(int _n){n=_n,m=0,clr_all(g,-1);}
void insert(int u,int v,type uf,type vf=0){
edg[m].to=v,edg[m].flow=uf,edg[m].next=g[u],g[u]=m++;