Reverse Left Words

include/offer_58.hpp

@@ -0,0 +1,14 @@
+#ifndef OFFER_58_HPP
+#define OFFER_58_HPP
+
+#include <string>
+
+using namespace std;
+
+class Solution {
+ public:
+  string reverseLeftWords(string s, int n);
+  void reverseSubStr(string &s, int begin, int end);
+};
+
+#endif

include/s0151_reverse_words_in_a_string.hpp

@@ -7,6 +7,7 @@ using namespace std;
 
 class Solution {
  public:
+  void reverseSubStr(string &s, int begin, int end);
   string reverseWords(string s);
 };
 

src/offer_58.cpp

@@ -0,0 +1,17 @@
+#include "offer_58.hpp"
+
+void Solution::reverseSubStr(string &s, int begin, int end) {
+  for (; begin < end; ++begin, --end) {
+    char tmp = s[begin];
+    s[begin] = s[end];
+    s[end] = tmp;
+  }
+}
+
+string Solution::reverseLeftWords(string s, int n) {
+  int len = s.length();
+  reverseSubStr(s, 0, n - 1);
+  reverseSubStr(s, n, len - 1);
+  reverseSubStr(s, 0, len - 1);
+  return s;
+}

src/s0151_reverse_words_in_a_string.cpp

@@ -1,14 +1,5 @@
 #include "s0151_reverse_words_in_a_string.hpp"
 
-// reverse a substring
-void reverseSubStr(string &s, int begin, int end) {
-  for (; begin < end; ++begin, --end) {
-    auto tmp = s[begin];
-    s[begin] = s[end];
-    s[end] = tmp;
-  }
-}
-
 string Solution::reverseWords(string s) {
   if (s.length() == 0) {
     return s;

tests/offer_58.cpp

@@ -0,0 +1,19 @@
+#include "offer_58.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(Offer58, Case1) {
+  string s{"abcdefg"};
+  int k{2};
+  string expected{"cdefgab"};
+  Solution solution;
+  EXPECT_EQ(solution.reverseLeftWords(s, k), expected);
+}
+
+TEST(Offer58, Case2) {
+  string s{"lrloseumgh"};
+  int k{6};
+  string expected{"umghlrlose"};
+  Solution solution;
+  EXPECT_EQ(solution.reverseLeftWords(s, k), expected);
+}