Java 4 lines Beats 100%
\n public int rangeSumBST(TreeNode root, int L, int R) {\n        if(root == null) return 0;\n        if(root.val > R) return rangeSumBST(root.left, L, R);\n   
```\n public int rangeSumBST(TreeNode root, int L, int R) {\n        if(root == null) return 0;\n        if(root.val > R) return rangeSumBST(root.left, L, R);\n        if(root.val < L) return rangeSumBST(root.right, L, R);\n        return root.val + rangeSumBST(root.left, L, R) + rangeSumBST(root.right, L, R);      \n    }\n```
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