Update code with contain and add code with insert contain checking

Author: colorbox

141/with_set.cpp

@@ -5,7 +5,7 @@ class Solution {
         set<ListNode*> reached;
         ListNode* current = head;
         while (current) {
-            if (reached.count(current)) {
+            if (reached.contains(current)) {
                 return true;
             }
             reached.insert(current);

141/with_set_2.cpp

@@ -0,0 +1,14 @@
+// insertの返り値を利用して存在確認をする方法
+class Solution {
+public:
+    bool hasCycle(ListNode *head) {
+        set<ListNode*> reached;
+        ListNode* current = head;
+        while (current) {
+            auto [it, inserted] = reached.insert(current);
+            if (!inserted) { return true; }
+            current = current->next;
+        }
+        return false;
+    }
+};