Symmetric Tree

Author: parshva45

Symmetric Tree.js

@@ -0,0 +1,38 @@
+/*Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
+
+For example, this binary tree [1,2,2,3,4,4,3] is symmetric:
+
+    1
+   / \
+  2   2
+ / \ / \
+3  4 4  3
+But the following [1,2,2,null,3,null,3] is not:
+    1
+   / \
+  2   2
+   \   \
+   3    3*/
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {boolean}
+ */
+var isSymmetric = function(root) {
+    return root == null || isSymmetricHelper(root.left,root.right)
+};
+
+var isSymmetricHelper = function(left,right){
+    if(left == null || right == null)
+        return left == right
+    if(left.val != right.val)
+        return false
+    return isSymmetricHelper(left.left,right.right) && isSymmetricHelper(left.right,right.left)
+};