[模板] SAP

int dfs(int x,int flow){  
    if(x==T) return flow;  
    int tmp=res=0;  
    for(int i=last[x];i;i=next[i]) if (d[x]==d[v[i]]+1 && w[i]>0){  
        last[x]=i;  
        tmp=dfs(v[i],min(flow-res,w[i]);  
        res+=tmp;w[i]-=tmp;w[i^1]+=tmp;  
        if (res==flow) return flow;  
    }  
    if (d[1]>=n) return res;  
    vd[d[x]]--; if (vd[d[x]]==0) d[1]=n;  
    d[x]++;vd[d[x]]++;  
    last[x]=top[x];  
        return res;  
}  

int SAP{  
    memset(d,0,sizeof(d));  
    memset(vd,0,sizeof(vd);  
    for (int i=1;i<=n;i++) last[i]=top[i];  
    int ans=0;  
    while (d[1]<n) ans+=dfs(S,1e9);  
    return ans;  
}