Search Range in Binary Search Tree
Given two values k1 and k2 (where k1 < k2) and a root pointer to a Binary Search Tree. Find all the keys of tree in range k1 to k2. i.e. print all x such that k1<=x<=k2 and x is a key of given BST. Return all the keys in ascending order.
Example
For example, if k1 = 10 and k2 = 22, then your function should print 12, 20 and 22.
20
/ \
8 22
/ \
4 12
public ArrayList<Integer> searchRange(TreeNode root, int k1, int k2) { ArrayList<Integer> result = new ArrayList<>(); searchRangeHelper(root, k1, k2, result); return result; } public void searchRangeHelper(TreeNode root, int min, int max, ArrayList<Integer> result) { if (root == null || min > max) { return; } if (root.val < min) { searchRangeHelper(root.right, min, max, result); } else if (root.val > max) { searchRangeHelper(root.left, min, max, result); } else { searchRangeHelper(root.left, min, root.val - 1, result); result.add(root.val); searchRangeHelper(root.right, root.val + 1, max, result); } }