NeedsParentheses.c

bool needsParentheses(struct node* p, bool rgt) { 

return (
  // (a + b) / c
  !rgt && precedence(p) < precedence(p->lft)) ||
  
  // case where right operation has precedence
  // for example: a + (b * c)
  (rgt && precedence(p) < precedence(p->rgt)) ||
  
  // case where the precedence is equal
  // for example: a - (b - c)
  ( 
  rgt && precedence(p) == precedence(p->rgt) && 
  (p->val == "-" || p->val == "/") 
  ); 
}