BZOJ 2427: [HAOI2010]软件安装 tarjan + 树形背包

Code: 

#include<bits/stdc++.h>
using namespace std;  
#define setIO(s) freopen(s".in","r",stdin)  
#define maxn 600 
int edges,n,m; 
int w[maxn],cost[maxn],hd[maxn],to[maxn<<1],nex[maxn<<1],val[maxn];    
void addedge(int u,int v)
{
    nex[++edges]=hd[u],hd[u]=edges,to[edges]=v; 
}
map<int,int>M[maxn]; 
int num,scc;  
vector<int>G[maxn]; 
stack<int>S; 
int dfn[maxn],low[maxn],W[maxn],V[maxn],idx[maxn],vis[maxn];   
void tarjan(int u) 
{
    low[u]=dfn[u]=++scc,vis[u]=1; 
    S.push(u); 
    for(int i=hd[u];i;i=nex[i]) 
    {
        int v=to[i]; 
        if(!vis[v]) tarjan(v), low[u]=min(low[u],low[v]); 
        else if(vis[v]==1) low[u]=min(low[u],dfn[v]); 
    }
    if(low[u]==dfn[u]) 
    {
        ++num; 
        for(;;) 
        {
            int x=S.top(); S.pop();
            vis[x]=-1;  
            W[num]+=cost[x], V[num]+=val[x], idx[x]=num; 
            if(x==u) break;            
        }
    }
}
int f[maxn][1200],tmp[maxn][1200],du[maxn];   
void solve(int x) 
{    
    for(int i=W[x];i<=m;++i) f[x][i]=V[x];      
    for(int i=0;i<G[x].size();++i)
    {
        int v=G[x][i]; 
        solve(v); 
        for(int j=m-W[x];j>=0;--j) 
        {
            for(int q=0;q<=j;++q) 
            { 
                f[x][W[x]+j]=max(f[x][W[x]+j], f[x][W[x]+j-q] + f[v][q]);   
            }
        }
    }
}
int main()
{ 
    int i,j; 
    // setIO("input");  
    scanf("%d%d",&n,&m); 
    for(i=1;i<=n;++i) scanf("%d",&cost[i]); 
    for(i=1;i<=n;++i) scanf("%d",&val[i]); 
    for(i=1;i<=n;++i) 
    {
        int x; 
        scanf("%d",&x); 
        addedge(x,i);              
    }
    for(i=1;i<=n;++i) if(!vis[i]) tarjan(i); 
    for(i=1;i<=n;++i) 
    {
        int cur=idx[i]; 
        for(j=hd[i];j;j=nex[j]) 
        { 
            int v=idx[to[j]];   
            if(cur!=v&&!M[cur][v]) 
            {
                M[cur][v]=1;   
                G[cur].push_back(v); 
                ++du[v];  
            }
        }
    }
    for(i=1;i<=num;++i) if(du[i]==0) G[0].push_back(i); 
    solve(0); 
    printf("%d\n",f[0][m]); 
    return 0; 
}

标签：tarjan,int,2427,vis,num,maxn,low,HAOI2010,dfn
来源： https://www.cnblogs.com/guangheli/p/11191810.html