title: What is the exact definition of a Weight balanced tree?
body: <p>There are many definitions given for a weight balanced tree. I got confused which one to follow and it is difficult to understand the definitions given.</p>
  
  <blockquote>
    <p>A node is balanced if weight[n.left] ≥ weight[n] and weight[n.right] ≥
    weight[n]</p>
    
    <p>Number of nodes in the left and right sub tree must be equal</p>
    
    <p>A weight-balanced tree is a binary tree in which for each node, the
    number of nodes in the left sub tree is at least half and at most
    twice the number of nodes in the right sub tree.</p>
  </blockquote>
  
  <p>Can somebody explain me which is the correct one?</p>