Create RangeSumOfBST.java

Author: techieJarek

RangeSumOfBST.java

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+/**
+ * Given the root node of a binary search tree, return the sum of values of all nodes with value between L and R (inclusive).
+ *
+ * The binary search tree is guaranteed to have unique values.
+ *
+ *
+ *
+ * Example 1:
+ *
+ * Input: root = [10,5,15,3,7,null,18], L = 7, R = 15
+ * Output: 32
+ * Example 2:
+ *
+ * Input: root = [10,5,15,3,7,13,18,1,null,6], L = 6, R = 10
+ * Output: 23
+ *
+ *
+ * Note:
+ *
+ * The number of nodes in the tree is at most 10000.
+ * The final answer is guaranteed to be less than 2^31.
+ */
+public class RangeSumOfBST {
+    public static void main(String[] args){
+        int L = 7, R = 15;
+        RangeSumOfBST helper = new RangeSumOfBST();
+        System.out.println(
+                "Range Sum of [" + L + "," + R + "] is : " + helper.rangeSumBST(helper.getTreeRootNode(), L, R));
+    }
+    public int rangeSumBST(TreeNode root, int L, int R) {
+        return getRangeSum(0, root, L, R);
+    }
+
+    private int getRangeSum(int currentSum, TreeNode root, int L, int R){
+        if(root == null) return 0;
+        int sum = getRangeSum(currentSum, root.left, L, R);
+        if(root.val >= L && root.val <=R){
+            sum += root.val;
+        }
+        return sum + getRangeSum(sum, root.right, L, R);
+    }
+
+    public class TreeNode {
+        int val;
+        TreeNode left;
+        TreeNode right;
+        TreeNode(int x) { val = x; }
+    }
+
+    public TreeNode getTreeRootNode(){
+        TreeNode root = new TreeNode(10);
+        root.left = new TreeNode(5);
+        root.left.left = new TreeNode(3);
+        root.left.right = new TreeNode(7);
+        root.right = new TreeNode(15);
+        root.right.right = new TreeNode(18);
+        return root;
+    }
+}