P2515 [HAOI2010]软件安装

#include<cstdio>
#include<iostream>
using namespace std;
#define ull unsigned long long
#define ll long long
#define R register int
#define pause (for(R i=1;i<=10000000000;++i))
#define In freopen("NOIPAK++.in","r",stdin)
#define Out freopen("out.out","w",stdout)
namespace Fread {
static char B[1<<15],*S=B,*D=B;
#ifndef JACK
#define getchar() (S==D&&(D=(S=B)+fread(B,1,1<<15,stdin),S==D)?EOF:*S++)
#endif
inline int g() {
    R ret=0,fix=1; register char ch; while(!isdigit(ch=getchar())) fix=ch==‘-‘?-1:fix;
    if(ch==EOF) return EOF; do ret=ret*10+(ch^48); while(isdigit(ch=getchar())); return ret*fix;
} inline bool isempty(const char& ch) {return (ch<=36||ch>=127);}
inline void gs(char* s) {
    register char ch; while(isempty(ch=getchar()));
    do *s++=ch; while(!isempty(ch=getchar()));
}
} using Fread::g; using Fread::gs;

namespace Luitaryi {
const int N=110;
int n,m,cnt,num,top,cc;
int vr[N],nxt[N],fir[N],stk[N],c[N];
int w[N],v[N],fa[N],dfn[N],low[N];
bool vis[N];
inline void add(int u,int v) {vr[++cnt]=v,nxt[cnt]=fir[u],fir[u]=cnt;}
inline void tarjan(int u) {
    dfn[u]=low[u]=++num; stk[++top]=u,vis[u]=true;
    for(R i=fir[u];i;i=nxt[i]) { R v=vr[i];
        if(!dfn[v]) {
            tarjan(v);
            low[u]=min(low[u],low[v]);
        } else if(vis[v]) low[u]=min(low[u],dfn[v]);
    } if(dfn[u]==low[u]) {
        ++cc; R tmp;
        do {
            tmp=stk[top],--top,c[tmp]=cc,vis[tmp]=false;
        } while(tmp!=u);
    }
}
int f[N][510];
int W[N],V[N];
int vv[N],nn[N],ff[N],d[N],cnte;
inline void adde(int u,int v) {vv[++cnte]=v,nn[cnte]=ff[u],ff[u]=cnte;}
inline void solve() {
    for(R u=1;u<=n;++u) {
        W[c[u]]+=w[u],V[c[u]]+=v[u];
        for(R i=fir[u];i;i=nxt[i]) { R v=vr[i];
            if(c[u]!=c[v]) adde(c[u],c[v]),++d[c[v]];
        }    
    }
}
inline void dfs(int u) {
    for(R i=V[u];i<=m;++i) f[u][i]=W[u];//初始化背包 
    for(R i=ff[u];i;i=nn[i]) { R v=vv[i];
        dfs(v); 
        for(R j=m;j>=V[u];--j) for(R k=0;k<=j-V[u];++k)
            f[u][j]=max(f[u][j],f[u][j-k]+f[v][k]);//注意必须给自己留一个V[u]，因为必须放下自己这个点，才能放儿子 
    }
}
inline void main() {
    n=g(),m=g(); for(R i=1;i<=n;++i) v[i]=g();
    for(R i=1;i<=n;++i) w[i]=g(); 
    for(R i=1,x;i<=n;++i) x=g(),x?add(x,i):void(0);
    for(R i=1;i<=n;++i) if(!dfn[i]) tarjan(i);
    solve(); for(R i=1;i<=cc;++i) d[i]==0?adde(0,i):void(0);
    dfs(0); printf("%d\n",f[0][m]);
}
}
signed main() {
    Luitaryi::main();
}