左孩子结点和右孩子结点都为空的结点就是叶子结点

int numberOfLeavesInBTusingLevelOrder(BinaryTreeNode  root){
  BinaryTreeNode temp;
  LLQueue q = new LLQueue();
  int count = 0;
  if(root == null){
    return 0;
  }
  q.enQueue(root);
  while(!q.isEmpty()){
    temp = q.deQueue();
    if(temp.getLeft() == null && temp.getRight() == null)
     count++;
    else{
      if(temp.getLeft() != null){
        q.enQueue(temp.getLeft());
      }
      if(temp.getRight()){
        q.enQueue(temp.getRight());
      }
    }
  }
  q.deleteQueue();
  return count;

}