规范格式

leetcode/0141.Linked-List-Cycle/141. Linked List Cycle.go

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+package leetcode
+
+import (
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+// ListNode define
+type ListNode = structures.ListNode
+
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+
+func hasCycle(head *ListNode) bool {
+	fast := head
+	slow := head
+	for slow != nil && fast != nil && fast.Next != nil {
+		fast = fast.Next.Next
+		slow = slow.Next
+		if fast == slow {
+			return true
+		}
+	}
+	return false
+}

leetcode/0141.Linked-List-Cycle/141. Linked List Cycle_test.go

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+package leetcode
+
+import "testing"
+
+func Test_Problem141(t *testing.T) {
+}

leetcode/0141.Linked-List-Cycle/README.md

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+# [141. Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/description/)
+
+## 题目
+
+Given a linked list, determine if it has a cycle in it.
+
+Follow up:   
+Can you solve it without using extra space?
+
+
+
+## 题目大意
+
+判断链表是否有环，不能使用额外的空间。
+
+## 解题思路
+
+给 2 个指针，一个指针是另外一个指针的下一个指针。快指针一次走 2 格，慢指针一次走 1 格。如果存在环，那么前一个指针一定会经过若干圈之后追上慢的指针。