Dec 23

Author: siddydutta

2024-12-December-LeetCoding-Challenge/Minimum Number of Operations to Sort a Binary Tree by Level.py

@@ -0,0 +1,70 @@
+from collections import deque
+from typing import Optional
+
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+class Solution:
+    def _get_min_swaps(self, level_vals):
+        swaps = 0
+        idx_map = {val: idx for idx, val in enumerate(level_vals)}
+        sorted_vals = sorted(level_vals)
+
+        for i in range(len(level_vals)):
+            if level_vals[i] == sorted_vals[i]:
+                continue
+            swaps += 1
+            cur_pos = idx_map[sorted_vals[i]]
+            idx_map[level_vals[i]] = cur_pos
+            level_vals[cur_pos] = level_vals[i]
+        return swaps
+
+    def minimumOperations(self, root: Optional[TreeNode]) -> int:
+        queue = deque([root])
+        ops = 0
+        while queue:
+            level_vals = [node.val for node in queue]
+            ops += self._get_min_swaps(level_vals)
+            queue = [child for node in queue
+                     for child in filter(None, (node.left, node.right))]
+        return ops
+
+
+def main():
+    root = TreeNode(1)
+    root.left = TreeNode(4)
+    root.right = TreeNode(3)
+    root.left.left = TreeNode(7)
+    root.left.right = TreeNode(6)
+    root.right.left = TreeNode(8)
+    root.right.right = TreeNode(5)
+    root.right.left.left = TreeNode(9)
+    root.right.right.left = TreeNode(10)
+    assert Solution().minimumOperations(root) == 3
+
+    root = TreeNode(1)
+    root.left = TreeNode(3)
+    root.right = TreeNode(2)
+    root.left.left = TreeNode(7)
+    root.left.right = TreeNode(6)
+    root.right.left = TreeNode(5)
+    root.right.right = TreeNode(4)
+    assert Solution().minimumOperations(root) == 3
+
+    root = TreeNode(1)
+    root.left = TreeNode(2)
+    root.right = TreeNode(3)
+    root.left.left = TreeNode(4)
+    root.left.right = TreeNode(5)
+    root.right.left = TreeNode(6)
+    assert Solution().minimumOperations(root) == 0
+
+
+if __name__ == '__main__':
+    main()

2024-12-December-LeetCoding-Challenge/README.md

@@ -25,7 +25,7 @@
 | December 20 | [2415. Reverse Odd Levels of Binary Tree](https://leetcode.com/problems/reverse-odd-levels-of-binary-tree/) | Medium | Solved |
 | December 21 | [2872. Maximum Number of K-Divisible Components](https://leetcode.com/problems/maximum-number-of-k-divisible-components/) | Hard | Unsolved |
 | December 22 | [2940. Find Building Where Alice and Bob Can Meet](https://leetcode.com/problems/find-building-where-alice-and-bob-can-meet/) | Hard | Unsolved |
-| December 23 | []() |  |  |
+| December 23 | [2471. Minimum Number of Operations to Sort a Binary Tree by Level](https://leetcode.com/problems/minimum-number-of-operations-to-sort-a-binary-tree-by-level/) | Medium | Solved |
 | December 24 | []() |  |  |
 | December 25 | []() |  |  |
 | December 26 | []() |  |  |
@@ -39,5 +39,5 @@
 | Level  | Problems | Solved | Unsolved |
 | ---    | --- | --- | --- |
 | Easy   | 5 | 5 | 0 |
-| Medium | 15 | 9 | 6 |
+| Medium | 16 | 10 | 6 |
 | Hard   | 2 | 0 | 2 |