Time: 66 ms (50.00%), Space: 66.3 MB (63.70%) - LeetHub

Author: py3-coder

2471-minimum-number-of-operations-to-sort-a-binary-tree-by-level/2471-minimum-number-of-operations-to-sort-a-binary-tree-by-level.java

@@ -0,0 +1,58 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    public int minimumOperations(TreeNode root) {
+        int count = 0;
+        Queue<TreeNode> q = new LinkedList<>();
+        q.offer(root);
+        while(!q.isEmpty()) {
+            int size = q.size();
+            List<Integer> list = new ArrayList<>();
+            while(size-- > 0) {
+                TreeNode node = q.poll();
+                if(node.left != null) {
+                    q.offer(node.left);
+                    list.add(node.left.val);
+                }
+                if(node.right != null) {
+                    q.offer(node.right);
+                    list.add(node.right.val);
+                }
+            }
+            count += helper(list);
+        }
+        
+        return count;
+    }
+    
+    int helper(List<Integer> list) {
+        int swaps = 0;
+        int[] sorted = new int[list.size()];
+        for(int i=0; i<sorted.length; i++) sorted[i] = list.get(i);
+        Arrays.sort(sorted);
+        Map<Integer, Integer> ind = new HashMap<>();
+        for(int i=0; i<list.size(); i++) ind.put(list.get(i), i);
+        
+        for(int i=0; i<list.size(); i++) {
+            if(list.get(i) != sorted[i]) {
+                swaps++;
+                ind.put(list.get(i), ind.get(sorted[i]));
+                list.set(ind.get(sorted[i]), list.get(i));
+            }
+        }
+        return swaps;
+    }
+}