add new solutions

solutions/13/q1372/solution.go

@@ -0,0 +1,34 @@
+package q1372
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func zigZagLen(node *TreeNode, isLeft bool, curLen int) int {
+	if node == nil {
+		return 0
+	}
+	var l, r int
+	if isLeft {
+		l = zigZagLen(node.Left, true, 1)
+		r = zigZagLen(node.Right, false, curLen+1)
+	} else {
+		l = zigZagLen(node.Left, true, curLen+1)
+		r = zigZagLen(node.Right, false, 1)
+	}
+	return max(curLen, l, r)
+}
+
+func longestZigZag(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+	return max(
+		zigZagLen(root.Left, true, 1),
+		zigZagLen(root.Right, false, 1),
+	)
+}
+
+var _ = longestZigZag