add new solutions

solutions/1/q142/solution.go

@@ -0,0 +1,32 @@
+package q142
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func detectCycle(head *ListNode) *ListNode {
+	p1, p2 := head, head
+	for p1 != nil && p2 != nil {
+		p1 = p1.Next
+		p2 = p2.Next
+		if p2 != nil {
+			p2 = p2.Next
+		}
+		if p1 == p2 {
+			break
+		}
+	}
+	if p2 == nil {
+		return nil
+	}
+
+	p1 = head
+	for p1 != p2 {
+		p1 = p1.Next
+		p2 = p2.Next.Next
+	}
+	return p1
+}
+
+var _ = detectCycle