Reverse words (#188)

* add reverse words

* impl reverse words

* fix small

leetcode-cc/ReverseWords.hpp

@@ -0,0 +1,56 @@
+#include <stack>
+
+#include "TestHelper.h"
+#include "problem.h"
+#include "solution.h"
+
+using namespace std;
+
+IMPLEMENT_PROBLEM_CLASS(
+    PReverseWords, 151, DIFFI_MEDIUM, TOPIC_ALGORITHMS,
+    "Reverse Words in a String",
+    "Given an input string s, reverse the order of the words.", {"Stack"});
+
+class SReverseWords : public ISolution {
+ public:
+  size_t problemId() const override { return 151; }
+  string name() const override {
+    return ("Solution for " + string("Reverse Words in a String"));
+  }
+  string location() const override { return __FILE_NAME__; }
+  int test() const override {
+    return testHelper<string, string>(
+        {"the sky is blue", "  hello world  ", "a good   example"},
+        {"blue is sky the", "world hello", "example good a"},
+        [this](auto input) { return this->reverseWords(input); });
+  };
+  int benchmark() const override { return 0; }
+
+ private:
+  string reverseWords(string s) const {
+    stack<string> st = {};
+    string current = "";
+
+    for (const auto& c : s) {
+      if (c == ' ') {
+        if (current != "") {
+          st.push(std::move(current));
+        }
+      } else {
+        current += c;
+      }
+    }
+
+    if (current != "") st.push(current);
+
+    string res = "";
+    while (!st.empty()) {
+      auto word = st.top();
+      st.pop();
+      res += word;
+      if (!st.empty()) res += " ";
+    }
+
+    return res;
+  }
+};

runtime-cc/src/registration.cc

@@ -71,6 +71,7 @@
 #include "../leetcode-cc/RestoreIpAddresses.hpp"
 #include "../leetcode-cc/ReverseLinkedListII.hpp"
 #include "../leetcode-cc/ReverseNodesinKGroup.hpp"
+#include "../leetcode-cc/ReverseWords.hpp"
 #include "../leetcode-cc/RomanToInteger.hpp"
 #include "../leetcode-cc/SameTree.hpp"
 #include "../leetcode-cc/ScrambleString.hpp"
@@ -653,5 +654,10 @@ const int registerAll(std::shared_ptr<Container> handle) {
   handle->registerSolution(
       []() -> ArcSolution { return std::make_shared<SMaxPointsLine>(); });
 
+  handle->registerProblem(
+      []() -> ArcProblem { return std::make_shared<PReverseWords>(); });
+  handle->registerSolution(
+      []() -> ArcSolution { return std::make_shared<SReverseWords>(); });
+
   return 0;
 }