add new solutions

solutions/1/q141/solution.go

@@ -0,0 +1,28 @@
+package q141
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func hasCycle(head *ListNode) bool {
+	if head == nil {
+		return false
+	}
+
+	p1, p2 := head, head
+	for {
+		for range 2 {
+			p2 = p2.Next
+			switch p2 {
+			case nil:
+				return false
+			case p1:
+				return true
+			}
+		}
+		p1 = p1.Next
+	}
+}
+
+var _ = hasCycle