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  4. Trees: Is This a Binary Search Tree?
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Trees: Is This a Binary Search Tree?

  • domingos_soares + 1 comment

    Java

    boolean checkBST(Node root) {
        return recursiveCheck(root, -1, 10001);       
    }

    boolean recursiveCheck(Node root, int min, int max){
        
        if(root == null)
            return true;
    
        if(root.data <= min || root.data >= max)
            return false;

        return(recursiveCheck(root.left, min, root.data) && recursiveCheck(root.right, root.data, max));
                

    }
    • this1 + 1 comment

      Is the equal in >= from:

      if(root.data <= min || root.data >= max)

      ...ever reached? Wouldn't the equivalence in <= be reached first and then never needing the second one? Therefore only needing this:

      if(root.data <= min || root.data > max)

      • rcl0000zk + 0 comments

        Consider the two invalid cases below. Domingos solution accounts for both.

        Case 1:

          5
 / \
5   8

        Case 2:

          5
 / \
3   5