左旋转字符串

include/jianzhi_offer.h

@@ -35,6 +35,14 @@ public:
      */
     bool is_number(std::string s);
 
+    /**
+     * 剑指 Offer 58 - II. 左旋转字符串
+     *
+     * @url   https://leetcode.cn/leetbook/read/illustration-of-algorithm/589fz2/
+     * @param s
+     * @param n
+     * @return
+     */
     std::string reverse_left_words(std::string s, int n);
 };
 
@@ -55,6 +63,16 @@ public:
 
     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);
 };
 
 
@@ -95,19 +113,6 @@ public:
 private:
     std::stack<int> _stk;
     std::stack<int> _min_stk;
-
-    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/string.cpp

@@ -1,6 +1,25 @@
 #include "jianzhi_offer.h"
 
 namespace yaha {
+
+std::string String::reverse_left_words(std::string s, int n) {
+//    方法1： 遍历
+//    std::string cur_str;
+//    std::string new_str;
+//    for (int i = 0; i < s.length(); ++i) {
+//        if (i < n) {
+//            cur_str += s[i];
+//        } else {
+//            new_str += s[i];
+//        }
+//    }
+//
+//    return new_str + cur_str;
+
+//    方法2： 内置函数
+    return s.substr(n, s.size()) + s.substr(0, n);
+}
+
 std::string String::replace_space(std::string s) {
     std::string result;
     for (int i = 0; i < s.length(); ++i) {

tests/jianzhi_offer/string_test.cpp

@@ -17,3 +17,10 @@ TEST(IsNumberTest, BasicAssertions) {
     ASSERT_FALSE(s.is_number("e"));
     ASSERT_FALSE(s.is_number("e9"));
 }
+
+TEST(ReverseLeftWords, BasicAssertions) {
+    yaha::String s;
+    ASSERT_EQ("cdefgab", s.reverse_left_words("abcdefg", 2));
+    ASSERT_EQ("umghlrlose", s.reverse_left_words("lrloseumgh", 6));
+}
+