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| /** | |
| * Definition of TreeNode: | |
| * public class TreeNode { | |
| * public int val; | |
| * public TreeNode left, right; | |
| * public TreeNode(int val) { | |
| * this.val = val; | |
| * this.left = this.right = null; | |
| * } | |
| * } | |
| */ | |
| // Approach #1 - More Readable recursion | |
| public class Solution { | |
| /** | |
| * @param root: the root node | |
| * @param L: an integer | |
| * @param R: an integer | |
| * @return: the sum | |
| */ | |
| public int rangeSumBST(TreeNode root, int L, int R) { | |
| // write your code here. | |
| if (root == null || L > R) { | |
| return 0; | |
| } | |
| int ans = (L <= root.val && root.val <= R) ? root.val : 0; | |
| if (root.val > L) { | |
| ans += rangeSumBST(root.left, L, R); | |
| } | |
| if (root.val < R) { | |
| ans += rangeSumBST(root.right, L, R); | |
| } | |
| return ans; | |
| } | |
| } | |
| // Approach #2 - Tail recursion | |
| // public class Solution { | |
| // /** | |
| // * @param root: the root node | |
| // * @param L: an integer | |
| // * @param R: an integer | |
| // * @return: the sum | |
| // */ | |
| // public int rangeSumBST(TreeNode root, int L, int R) { | |
| // // write your code here. | |
| // if (root == null || L > R) { | |
| // return 0; | |
| // } | |
| // return rangeSumBST(root.left, L, R) + | |
| // rangeSumBST(root.right, L, R) + | |
| // ((root.val >= L && root.val <= R) ? root.val : 0); | |
| // } | |
| // } |
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