链表反转

include/jianzhi_offer.h

@@ -7,9 +7,6 @@
 namespace yaha {
 class CQueue {
 public:
-    CQueue() {
-    }
-
     void append_tail(int value);
     int delete_head();
 
@@ -20,7 +17,22 @@ private:
 
 class String {
 public:
+    /**
+     * 剑指 Offer 09. 用两个栈实现队列
+     *
+     * @url   https://leetcode.cn/leetbook/read/illustration-of-algorithm/5d3i87/
+     * @param s
+     * @return
+     */
     std::string replace_space(std::string s);
+
+    /**
+     * 剑指 Offer 20. 表示数值的字符串
+     *
+     * @url   https://leetcode.cn/leetbook/read/illustration-of-algorithm/5d6vi6/
+     * @param s
+     * @return
+     */
     bool is_number(std::string s);
 };
 
@@ -29,9 +41,28 @@ public:
     int val;
     ListNode *next;
     ListNode(int x) : val(x), next(NULL) {}
+
+    /**
+     * 剑指 Offer 06. 从尾到头打印链表
+     *
+     * @url   https://leetcode.cn/leetbook/read/illustration-of-algorithm/5dt66m/
+     * @param head
+     * @return
+     */
     std::vector<int> reverse_print(ListNode *head);
-    void reverse_stack(ListNode *head, std::vector<int>& res);
-    void reverse(ListNode *head, std::vector<int>& res);
+
+    void reverse_stack(ListNode *head, std::vector<int> &res);
+    void reverse(ListNode *head, std::vector<int> &res);
+
+    /**
+     * 剑指 Offer 24. 反转链表
+     *
+     * @url   https://leetcode.cn/leetbook/read/illustration-of-algorithm/9pdjbm/
+     * @param head
+     * @return
+     */
+    ListNode *reverse_list(ListNode *head);
+    ListNode* reverse_list(ListNode* cur, ListNode* pre);
 };
 
 }

src/jianzhi_offer/list_node.cpp

@@ -29,4 +29,32 @@ std::vector<int> ListNode::reverse_print(ListNode *head) {
     return res;
 }
 
+ListNode* ListNode::reverse_list(ListNode* cur, ListNode* pre) {
+    if (cur == nullptr) {
+        return pre;
+    }
+    ListNode* res = reverse_list(cur->next, cur);
+    cur->next = pre;
+    return res;
+}
+
+ListNode *ListNode::reverse_list(ListNode *head) {
+    ListNode* cur = head;
+    ListNode* pre = nullptr;
+
+    while (cur) {
+//        链表转存
+        ListNode* tmp = cur->next;
+//        链表断开
+        cur->next = pre;
+//        将当前链表值赋值给最后一个
+        pre = cur;
+        cur = tmp;
+    }
+
+    return pre;
+
+//    return reverse_list(head, nullptr);
+}
+
 }

tests/jianzhi_offer/list_node_test.cpp

@@ -2,6 +2,9 @@
 
 #include "jianzhi_offer.h"
 
+/**
+ * 剑指 Offer 06. 从尾到头打印链表
+ */
 TEST(NodeListTest, BasicAssertions) {
     yaha::ListNode *node = new yaha::ListNode(1);
     node->next = new yaha::ListNode(3);
@@ -22,3 +25,22 @@ TEST(NodeListStackTest, BasicAssertions) {
     ASSERT_EQ(3, res[1]);
     ASSERT_EQ(1, res[2]);
 }
+
+/**
+ * 剑指 Offer 24. 反转链表
+ */
+TEST(ListReverseTest, BasicAssertions) {
+    yaha::ListNode *node = new yaha::ListNode(1);
+    node->next = new yaha::ListNode(2);
+    node->next->next = new yaha::ListNode(3);
+    node->next->next->next = new yaha::ListNode(4);
+    node->next->next->next->next = new yaha::ListNode(5);
+
+    auto l = node->reverse_list(node);
+    ASSERT_EQ(5, l->val);
+    ASSERT_EQ(4, l->next->val);
+    ASSERT_EQ(3, l->next->next->val);
+    ASSERT_EQ(2, l->next->next->next->val);
+    ASSERT_EQ(1, l->next->next->next->next->val);
+
+}