[上下界费用流] BZOJ2055 80人环游世界

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#include<cstdio>#include<cstdlib>#include<algorithm>#include<cstring>#define V G[p].v#define oo 1<<30using namespace std;inline char nc(){static char buf[100000],*p1=buf,*p2=buf;if (p1==p2) { p2=(p1=buf)+fread(buf,1,100000,stdin); if (p1==p2) return EOF; }return *p1++;}inline void read(int &x){char c=nc(),b=1;for (;!(c>='0' && c<='9');c=nc()) if (c=='-') b=-1;for (x=0;c>='0' && c<='9';x=x*10+c-'0',c=nc()); x*=b;}struct edge{int u,v,w,f;int next;};edge G[1000005];int head[215],inum=1;inline void add(int u,int v,int f,int w,int p){G[p].u=u; G[p].v=v; G[p].f=f; G[p].w=w; G[p].next=head[u]; head[u]=p;}inline void link(int u,int v,int f,int w){add(u,v,f,w,inum+=2),add(v,u,0,-w,inum-1);}int s,t,S,T,Mincost;const int NQ=1000;int Q[NQ],l,r;int dis[215],ins[215],pre[215];inline bool SPFA(){int u;for (int i=1;i<=T;i++) dis[i]=1<<30,pre[i]=0,ins[i]=0;memset(Q,0,sizeof(Q));l=r=-1; Q[(++r)%NQ]=S; dis[S]=0; ins[S]=1;while (l!=r){u=Q[(++l)%NQ]; ins[u]=0;for (int p=head[u];p;p=G[p].next)if (G[p].f && dis[V]>dis[u]+G[p].w){dis[V]=dis[u]+G[p].w; pre[V]=p;if (!ins[V])Q[(++r)%NQ]=V,ins[V]=1;}}if (dis[T]==1<<30) return false;int minimum=1<<30;for (int p=pre[T];p;p=pre[G[p].u])minimum=min(minimum,G[p].f);for (int p=pre[T];p;p=pre[G[p].u]){G[p].f-=minimum; G[p^1].f+=minimum;Mincost+=G[p].w*minimum;}return true;}int n,m;int main(){int x;freopen("t.in","r",stdin);freopen("t.out","w",stdout);read(n); read(m);s=2*n+1,t=2*n+2; S=2*n+3; T=2*n+4;link(t,s,m,0);for (int i=1;i<=n;i++){read(x);link(S,i<<1,x,0);link(i*2-1,T,x,0);link(s,i*2-1,oo,0);link(i<<1,t,oo,0);}for (int i=1;i<=n;i++)for (int j=i+1;j<=n;j++){read(x);if (~x) link(i<<1,j*2-1,oo,x);}while (SPFA());printf("%d\n",Mincost);return 0;}

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