树中节点结构为:

typedef struct TreeNode

{

int data;

TreeNode * left;

TreeNode * right;

TreeNode * parent;

}TreeNode;

void pre_order(TreeNode * Node)

{

if(Node != NULL)

{

printf("%d ", Node->data);

pre_order(Node->left);

pre_order(Node->right);

}

}

调用时: pre_order(Root); //Root为树的根

核心代码:

procedure first(i:longint);

begin

write(a);

if a[i*2]<>0 then first(i*2);

if a[i*2+1]<>0 then first(i*2+1);

end;