Create 101-symmetric-tree.js

Author: everthis

101-symmetric-tree.js

@@ -0,0 +1,31 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {boolean}
+ */
+const isSymmetric = function(root) {
+    if(root == null) return true
+    return compare(root.left, root.right)
+};
+
+function compare(l, r) {
+    if(l == null && r == null) return true
+    if( (l == null && r != null) || (l != null && r == null) ) return false
+    
+    if(l.val === r.val) {
+        if(compare(l.left, r.right) !== false && compare(l.right, r.left) !== false) {
+           return true
+         } else {
+             return false
+         }
+        
+    } else {
+        return false
+    }
+}