代码：

#include <bits/stdc++.h>
using namespace std;
int n, q;

struct node {
	node *father;
	bool colour;
} a[100000];

void bfs(int x) {
	queue<node>q;
	q.push(a[x]);
	a[x].colour = !a[x].colour;
	while (!q.empty()) {
		int flag = 0;
		for (int i = 1; i < n; i++) {
			if (a[i].father == q.front()) {//编译错误
				q.push(a[i]);
				a[i].colour = !a[i].colour;
				flag++;
				if (flag == 2) {
					q.pop();
					flag = 0;
				}
			}
		}
	}
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	for (int i = 1; i < n; i++) {
		int x;
		cin >> x;
		a[i].father = a[x];
	}
	for (int i = 0; i < n; i++) {
		char c;
		cin >> c;
		a[i].colour = c - '0';
	}
	cin >> q;
	while (q--) {
		int swch;
		cin >> swch;
		bfs(swch);
	}
	for (int i = 0; i < n; i++) {
		cout << a[i].colour;
	}
	return 0;
}

请问：怎么改才能避免编译错误？