从文件扫描以使用图形创建BT

Question

我需要使用图形方法创建一个二叉树，并且需要扫描文件中的节点数，每个节点索引和子级数。我使用了这段代码，但它总是给我一个异常，我该怎么办？ ps。（图形应为指向节点的指针数组）

#include<iostream>
#include<fstream>
using namespace std;
#define MAX_CHILD 2
struct NODE {
    int child[MAX_CHILD];
    int count_child;
};
void construct_graph(NODE* G[],int num)
{
    int n, index;
    ifstream fp("data.txt", ios::in);
    fp >> n;
    for (int i = 0; i < n; i++)
    {
        fp >> index;

        fp>>G[index]->count_child;
        for (int j = 0; j < G[index]->count_child; j++)
        {
            fp>>G[index]->child[j];
        }
    }
}
void df_visited(NODE *G[], bool visited[], int v, int*nw)
{
    if (visited[v])
        return;
    nw[v] = G[v]->count_child + 1;
    cout << nw[v];
    visited[v] = true;
    for (int i = 0; i < G[v]->count_child; i++)
    {
        df_visited(G, visited, G[v]->child[i], nw);
    }
}
void depth_first_print(NODE *G[], int size,int *nw)
{
    int i;
    bool *visited;
    visited = new bool[size];
    for (i = 0; i < size; i++)
        visited[i] = false;
    for (i = 0; i < size; i++)
    {
        if (!visited[i])
            df_visited(G, visited, i,nw);
    }

}
int main()
{
    NODE **G;
    int num;
    ifstream fp("data.txt", ios::in);
    fp >> num;
    G = new NODE*[num];
    construct_graph(G,num);
    int *node_weight;
    node_weight = new int[num];
    depth_first_print(G, num, node_weight);

    delete[]G;
    return 0;
}