题解

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#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int n;
int son[N][2];
int f[N], col[N], sum[N];

void dfs(int x, int now) {
    now += sum[x];
    if (now & 1) col[x] ^= 1;
    for (int i = 0; i < 2; i++) {
        if (son[x][i] != -1) dfs(son[x][i], now);
    }
}

int main() {
    cin >> n;
    memset(son, -1, sizeof son);
    for (int i = 2; i <= n; i++) {
        cin >> f[i];
        for (int j = 0; j < 2; j++) {
            if (son[f[i]][j] == -1) {
                son[f[i]][j] = i;
                break;
            }
        }
    }
    string s;
    cin >> s;
    for (int i = 1; i <= n; i++) {
        col[i] = s[i - 1] - '0';
    }
    int q;
    cin >> q;
    while (q--) {
        int x;
        cin >> x;
        sum[x] += 1;
    }
    dfs(1, 0);
    for (int i = 1; i <= n; i++) {
        cout << col[i];
    }
    cout << "\n";
}