find the next node of given node in binary search tree.

gistfile1.java

TreeNode findNextNode(TreeNode r){
  if (r==null) rerturn null;
  
  if(r.father==null||r.right!=null){
    
    return leftMost(r.right);
  }
  else{
    TreeNode x=n;
    TreeNode f=n.father;
    while(f!=null&&f.left!=x){
      x=f;
      f=f.father;
      
    }
    
    return f;
  }
  
  }
  public TreeNode leftMost(TreeNode r){
    if(r==null)return null;
    while(r.left!=null){
      
      r=r.left
    }
    return r;
  }