Solve the height of a binary tree non-recursively java

Ideas

Similar to the breadth-first algorithm of the graph, the null pointer is the sign of the end of the level traversal

Code

int findHeightOfBinaryTree(BinaryTreeNode root){
    
    
  int level = 1;
  LLQueue q = new LLQueue();
  if(root == null)
    return 0;
  q.enQueue(root);
  //作为分层遍历的标志
  q.enQueue(null);
  while(!q.isEmpty()){
    
    
    root = q.deQueue();
    //当前层遍历结束
    if(root == null){
    
    
      //如果该层非最深层，则为该层增加一个标记
      if(!q.isEmpty())
        q.enQueue(null);
      level++;
    }else{
    
    
      if(root.getLeft() != null){
    
    
        q.enQueue(root.getLeft());
      }
      if(root.getRight() != null){
    
    
        q.enQueue(root.getRight());
      }
    }
    return level;
  }

}