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Commit 43ebf23

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solves kth largest element in bst
1 parent 2bd9edd commit 43ebf23

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+28
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‎README.md‎

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| 226 | [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree) | [![Java](assets/java.png)](src/InvertBinaryTree.java) [![Python](assets/python.png)](python/invert_binary_tree.py) | |
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| 227 | [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii) | [![Java](assets/java.png)](src/BasicCalculatorII.java) | |
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| 229 | [Majority Element II](https://leetcode.com/problems/majority-element-ii) | [![Java](assets/java.png)](src/MajorityElementII.java) | |
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| 230 | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst) | | |
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| 230 | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst) | [![Java](assets/java.png)](src/KthSmallestElementInABST.java) | |
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| 231 | [Power of Two](https://leetcode.com/problems/power-of-two) | [![Java](assets/java.png)](src/PowerOf2.java) [![Python](assets/python.png)](python/is_power_of_2.py) | |
190190
| 232 | [Implement Queue Using Stacks](https://leetcode.com/problems/implement-queue-using-stacks) | [![Java](assets/java.png)](src/MyQueue.java) [![Python](assets/python.png)](python/implement_queue_using_stacks.py) | |
191191
| 234 | [Palindrome Linked Lists](https://leetcode.com/problems/palindrome-linked-list) | [![Java](assets/java.png)](src/PalindromeLinkedList.java) [![Python](assets/python.png)](python/palindrome_linked_list.py) | |

‎src/KthSmallestElementInABST.java‎

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// https://leetcode.com/problems/kth-smallest-element-in-a-bst
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// T: O(k + log(N))
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// S: O(log(N))
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import java.util.Stack;
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public class KthSmallestElementInABST {
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public int kthSmallest(TreeNode root, int k) {
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final Stack<TreeNode> stack = new Stack<>();
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addLeftPathToStack(root, stack);
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for (int count = 0 ; !stack.isEmpty() ; ) {
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final TreeNode current = stack.pop();
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count++;
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if (count == k) return current.val;
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addLeftPathToStack(current.right, stack);
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}
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return -1;
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}
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private void addLeftPathToStack(TreeNode root, Stack<TreeNode> stack) {
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if (root == null) return;
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stack.push(root);
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addLeftPathToStack(root.left, stack);
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}
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}

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