235. Lowest Common Ancestor of a Binary Search Tree

 /*
 */
 This is the code for the second time;
 public class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        
        if(p==null)
        return q;
        if(q==null)
        return p;
        if(p==root|q==root)
        return root;
        if((p.val>root.val&q.val<root.val)|(q.val>root.val&p.val<root.val))
        return root;
        if(p.val>root.val&q.val>root.val)
        return lowestCommonAncestor(root.right,p,q);
        else
        return lowestCommonAncestor(root.left,p,q);
        
        
    }
}
This is the first time
public class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root==null)
        return null;
        if(p==null)
        return q;
        if(q==null)
        return p;
        if(root.val==p.val|root.val==q.val)  // I forget this condition in the beginning, in the end if the root is 2, root.left
                                             //is 2,then q=1;  basically the return would be null rather than 2
        return root;
        if(root.left==null)
        {root=root.right;
        return lowestCommonAncestor(root,p,q);
            
        }
        else if(root.right==null)
        {
        return lowestCommonAncestor(root.left,p,q);
        }
        else
        {   int a=Math.max(p.val,q.val);
            int b=Math.min(p.val,q.val);
            if(b<root.val&&a<root.val)   //Be careful that do not lose .val, another thing is that compared to root, rather than root.left or root.right
            return lowestCommonAncestor(root.left,p,q);
            else if(b<root.val&&a>root.val)
            return root;
            else
            return lowestCommonAncestor(root.right,p,q);
            
        }
    }
}