data structures - BST Insertion issue -

my code bst insertion getting passed 3 test cases , failing other 3 test cases, test case hidden can't figure out i'm going wrong logic. please check , advise me other different test case logic not pass. here's code:

/* node defined   typedef struct node {    int data;    node * left;    node * right; }node;  */   node * insert(node * root, int value) { node* n;  n=root;  if(n!=null)     {while (true )      { if(n->data > value && n->left!=null){n=n->left;}       else if(n->data < value && n->right!=null){n=root->right;}       else              {  node* a=new node();              a->data=value;            if(n->data > value ){ n->left=a;break; }            else{ n->right=a;break; }             }    }  }  else  {node* a=new node();   a->data=value;   root=a;     } return root;  } 

i write

node*  insert(node * root, int value)     { node* n=  root;        node* a=new node();       if( == null )     { cout<<" no memory  \n " ; exit(0); }         a->data=value;        a->left=a->right=null;      if(n!=null)         {while (true )          { if(n->data > value  )              {   if( n->left!=null )                                  {n=n->left;}                   else                       {                            n->left=a;                            return root;                        }                                     }           else if(n->data < value  )               {  if (  n->right!=null )                             {n=n->right;}                  else                         {                          n->right = a;                          return root;                         }               }         }      }      else      {      return  a;         }      }