catch-up

symmetric-tree/sol.go

@@ -0,0 +1,38 @@
+package main
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func isSymmetric(root *TreeNode) bool {
+	if root == nil {
+		return true
+	}
+	queue := []*TreeNode{root}
+	for len(queue) != 0 {
+		l := len(queue)
+		current := queue
+		queue = queue[l:]
+		for idx, node := range current {
+			if (node == nil && current[l-idx-1] != nil) ||
+				(node != nil && current[l-idx-1] == nil) ||
+				(node != nil && node.Val != current[l-idx-1].Val) {
+				return false
+			}
+			if node != nil {
+				queue = append(queue, node.Left, node.Right)
+			}
+		}
+	}
+	return true
+}