From 9d09b11d56722748e00d3647cdcd228793baaa66 Mon Sep 17 00:00:00 2001
From: Guanzhong Pan <gpan20020205@gmail.com>
Date: Wed, 26 Jan 2022 09:26:03 +0000
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200143.=E9=87=8D=E6=8E=92?=
 =?UTF-8?q?=E9=93=BE=E8=A1=A8.md=20C=E8=AF=AD=E8=A8=80=E8=A7=A3=E6=B3=95?=
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---
 problems/0143.重排链表.md | 68 +++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/problems/0143.重排链表.md b/problems/0143.重排链表.md
index 4ea9cb97..00622623 100644
--- a/problems/0143.重排链表.md
+++ b/problems/0143.重排链表.md
@@ -439,7 +439,75 @@ var reorderList = function(head, s = [], tmp) {
 }
 ```
 
+### C
+方法三：反转链表
+```c
+//翻转链表
+struct ListNode *reverseList(struct ListNode *head) {
+    if(!head)
+        return NULL;
+    struct ListNode *preNode = NULL, *curNode = head;
+    while(curNode) {
+        //创建tempNode记录curNode->next（即将被更新）
+        struct ListNode* tempNode = curNode->next;
+        //将curNode->next指向preNode
+        curNode->next = preNode;
+        //更新preNode为curNode
+        preNode = curNode;
+        //curNode更新为原链表中下一个元素
+        curNode = tempNode;
+    }
+    return preNode;
+}
 
+void reorderList(struct ListNode* head){
+    //slow用来截取到链表的中间节点(第一个链表的最后节点)，每次循环跳一个节点。fast用来辅助，每次循环跳两个节点
+    struct ListNode *fast = head, *slow = head;
+    while(fast && fast->next && fast->next->next) {
+        //fast每次跳两个节点
+        fast = fast->next->next;
+        //slow每次跳一个节点
+        slow = slow->next;
+    }
+    //将slow->next后的节点翻转
+    struct ListNode *sndLst = reverseList(slow->next);
+    //将第一个链表与第二个链表断开
+    slow->next = NULL;
+    //因为插入从curNode->next开始，curNode刚开始已经head。所以fstList要从head->next开始
+    struct ListNode *fstLst = head->next;
+    struct ListNode *curNode = head;
+
+    int count = 0;
+    //当第一个链表和第二个链表中都有节点时循环
+    while(sndLst && fstLst) {
+        //count为奇数，插入fstLst中的节点
+        if(count % 2) {
+            curNode->next = fstLst;
+            fstLst = fstLst->next;
+        } 
+        //count为偶数，插入sndList的节点
+        else {
+            curNode->next = sndLst;
+            sndLst = sndLst->next;
+        }
+        //设置下一个节点
+        curNode = curNode->next;
+        //更新count
+        ++count;
+    }
+
+    //若两个链表fstList和sndLst中还有节点，将其放入链表
+    if(fstLst) {
+        curNode->next = fstLst;
+    }
+    if(sndLst) {
+        curNode->next = sndLst;
+    }
+
+    //返回链表
+    return head;
+}
+```
 
 
 -----------------------