LOJ 最大流加强版

#include 
    
     const int inf=0x7fffffff;const int maxn=1210;const int maxh=1<<20;using namespace std;int f[maxn][maxn];typedef unsigned short u16;vector
     
       out[maxn],act[maxn];#define count cntstruct nodelist{u16 l,r;}hlist[maxn];u16 height[maxn],count[maxn],hlisthead[maxn],que[maxn];short high,highact;int excess[maxn];int n,m,s,t;void ins(int t,int h){    int q=hlisthead[h];    int l=q?q:t;    int r=q?hlist[q].r:t;    hlist[t].l=l;    hlist[l].r=t;    hlist[t].r=r;    hlist[r].l=t;    hlisthead[h]=t;    height[t]=h;    ++count[h];}void del(int t,int h){    int l=hlist[t].l;    int r=hlist[t].r;    hlist[r].l=l;    hlist[l].r=r;    if(hlisthead[h]==t)        hlisthead[h]=l==t?0:l;    --count[h];}void ae(int u,int v,int c){f[u][v]+=c;}void regularize(){    for(int i=1;i<=n;++i)        for(int j=i+1;j<=n;++j)            if(f[i][j]||f[j][i])                out[i].push_back(j),out[j].push_back(i);}void push(int u,int v){    int df=min(excess[u],f[u][v]);    f[u][v]-=df;f[v][u]+=df;    excess[u]-=df;excess[v]+=df;    if(excess[v]>0&&excess[v]<=df)act[height[v]].push_back(v);}void grel(){    fill(height,height+(n+1),n);    memset(count,0,sizeof count);    memset(hlisthead,0,sizeof hlisthead);    int ql=0,qr=0;    for(ins(t,0),que[qr++]=t;ql!=qr;){        int u=que[ql++],h=height[u]+1;        for(int v:out[u])            if(height[v]==n&&f[v][u])                ins(v,h),que[qr++]=v;    }act[0].clear();    for(int i=1;i<=n;++i)        if(excess[i]>0)act[height[i]].push_back(i);    high=highact=height[que[qr-1]];}void discharge(int u){    int nm=n,h=height[u];    for(int v:out[u])if(f[u][v])        if(h==height[v]+1){            push(u,v);if(!excess[u])return;        }else nm=min(nm,height[v]+1);    if(count[h]==1){        for(int i=h;i<=high;++i)            while(hlisthead[i])height[hlisthead[i]]=n,del(hlisthead[i],i);        high=h-1;    }else{        del(u,h),height[u]=nm;        if(nm==n)return;        ins(u,nm);high=max(high,highact=nm);        act[nm].push_back(u);    }}int hlpp(){    if(s==t)return 0;    highact=high=0;height[s]=n;    excess[s]=inf;excess[t]=-inf;    for(int i:out[s])push(s,i);grel();    for(int u;highact>=0;)if(act[highact].empty())--highact;else u=act[highact].back(),act[highact].pop_back(),discharge(u);    return excess[t]+inf;}int main(){    scanf("%d%d%d%d",&n,&m,&s,&t);    for(int i=0,u,v,f;i