Trim a Binary Search Tree

Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might need to change the root of the tree, so the result should return the new root of the trimmed binary search tree.

Example 1:

Input:

    1

   / \

  0   2

  L = 1

  R = 2

Output:

    1

      \

       2

Example 2:

Input:

    3

   / \

  0   4

   \

    2

   /

  1

  L = 1

  R = 3

Output:

      3

     /

   2

  /

 1

 public TreeNode trimBST(TreeNode root, int L, int R) {

         if(root == null){

             return null;

         }else if(root.val >= L && root.val <= R){

             root.left = trimBST(root.left, L, R);

             root.right = trimBST(root.right, L, R);

             return root;

         }else if(root.val < L){

             return trimBST(root.right, L, R);

         }else if(root.val > R){

             return trimBST(root.left, L, R);

         }

         return null;

     }

巴特西

Trim a Binary Search Tree

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