请大佬帮我看一下哪里错了，提交之后总显示段错误？

#include <stdio.h>
#define MaxTree 10
#define Null -1
#define ElementType char
#define Tree int
struct TreeNode{
    ElementType Element;
    Tree left;
    Tree right;
}T1[MaxTree],T2[MaxTree];
Tree BuildTree(struct TreeNode T[]);
int isomorphic(Tree R1,Tree R2);
int main()
{
    Tree R1,R2;
    R1=BuildTree(T1);
    R2=BuildTree(T2);
    if(isomorphic(R1,R2)) printf("Yes\n");
    else printf("No\n");
    return 0;
}
Tree BuildTree(struct TreeNode T[]){
    int i,N;
    scanf("%d",&N);
    int check[N];
    Tree Root=-1;
    for(i=0;i<N;i++) check[i]=0;
    char cl,cr;    
    for(i=0;i<N;i++){
        scanf("%c %c %c",&T[i].Element,&cl,&cr);
        if(cl!='-'){
            T[i].left=cl-'0';
            check[T[i].left]=1;
        }
        else T[i].left=Null;
        if(cr!='-'){
            T[i].right=cr-'0';
            check[T[i].right]=1;
        }
        else T[i].right=Null;
    }
    for(i=0;i<N;i++){
        if(check[i]==0) {
            Root=i;
            break;
        }
    }
    return Root;
}
int isomorphic(Tree R1,Tree R2){
    if((R1==Null)&&(R2==Null)) return 1; //R1,R2都为空时
    if(((R1!=Null)&&(R2==Null))||((R1==Null)&&(R2!=Null))) return 0;//R1空R2不空或者R1不空R2空T
    if(T1[R1].Element!=T2[R2].Element) return 0;
    if((T1[R1].left==Null)&&(T2[R2].left==Null)) return isomorphic(T1[R1].right,T2[R2].right);
    if(((T1[R1].left!=Null)&&(T2[R2].left!=Null))&&(T1[T1[R1].left].Element==T2[T2[R2].left].Element))
        return isomorphic(T1[R1].left,T2[R2].left)&&isomorphic(T1[R1].right,T2[R2].right);
    else return isomorphic(T1[R1].left,T2[R2].right)&&isomorphic(T1[R1].right,T2[R2].left);
}