Create Cousins in Binary Tree II.java

varunu28 · web-flow · commit 975d71b3150d · 2024-10-23T06:42:23.000-07:00
diff --git a/Medium/Cousins in Binary Tree II.java b/Medium/Cousins in Binary Tree II.java
@@ -0,0 +1,44 @@
+/**
+ * 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 TreeNode replaceValueInTree(TreeNode root) {
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.add(root);
+        int prevLevelSum = root.val;
+        while (!queue.isEmpty()) {
+            int size = queue.size();
+            int levelSum = 0;
+            for (int i = 0; i < size; i++) {
+                TreeNode node = queue.remove();
+                node.val = prevLevelSum - node.val;
+                int siblingSum = (node.left != null ? node.left.val : 0) + 
+                    (node.right != null ? node.right.val : 0); 
+                if (node.left != null) {
+                    levelSum += node.left.val;
+                    node.left.val = siblingSum;
+                    queue.add(node.left);
+                }
+                if (node.right != null) {
+                    levelSum += node.right.val;
+                    node.right.val = siblingSum;
+                    queue.add(node.right);
+                }
+            }
+            prevLevelSum = levelSum;
+        }
+        return root;
+    }
+}
