【HAOI2010】软件安装

//缩点是为了处理图中的环，缩点之后就是一个简单的树型背包dp了
#include<bits/stdc++.h>
using namespace std;
const int N = 1e3 + 7;
int dp[N][N], W[N], V[N], w[N], v[N];
int head[N], ver[N], nex[N], tot, n, m;
int in[N], dfn[N], low[N], st[N], vis[N], c[N], cnt, top, num;
vector<int> scc[N];
void add(int x, int y) {
    ver[++tot] = y; nex[tot] = head[x]; head[x] = tot;
}
void tarjan(int x) {
    low[x] = dfn[x] = ++num;
    st[top++] = x;
    vis[x] = 1;
    for (int i = head[x]; i; i = nex[i]) {
        int y = ver[i];
        if (!dfn[y]) {
            tarjan(y);
            low[x] = min(low[x], low[y]);
        } else if (vis[y])
            low[x] = min(low[x], dfn[y]);
    }
    if (low[x] == dfn[x]) {
        int y;
        ++cnt;
        do {
            y = st[--top];
            vis[y] = 0;
            c[y] = cnt;
            v[cnt] += V[y];
            w[cnt] += W[y];
        } while (x != y);
    }
}
void Dp(int x) {
    for (int i = w[x]; i <= m; i++) dp[x][i] = v[x];
    for (int y: scc[x]) {
        Dp(y);
        for (int i = m - w[x]; i >= 0; i--) {
            for (int j = 0; j <= i; j++) {
                dp[x][i + w[x]] = max(dp[x][i + w[x]], dp[x][i + w[x] - j] + dp[y][j]);
            }
        }
    }
}
int main() {
    int x;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) cin >> W[i];
    for (int i = 1; i <= n; i++) cin >> V[i];
    for (int i = 1; i <= n; i++) {
        cin >> x;
        if (x) add(x, i);
    }
    for (int i = 1; i <= n; i++) if (!dfn[i]) tarjan(i);
    for (x = 1; x <= n; x++) {
        for (int j = head[x]; j; j = nex[j]) {
            int y = ver[j];
            if (c[x] != c[y]) scc[c[x]].push_back(c[y]), in[c[y]]++;
        }
    }
    for (int i = 1; i <= cnt; i++) {
        if (!in[i]) scc[0].push_back(i);
    }
    Dp(0);
    cout << dp[0][m] << endl;
    return 0;
}