Chapter 3: Add Exercise 3-5

asankov · May 9, 2020 · d15f071 · d15f071
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diff --git a/chapter-3/3.6-c++/README.md b/chapter-3/3.6-c++/README.md
@@ -2,3 +2,8 @@
 
 ### Section 3.6 C++
 **Summary:** Let's rewrite these stuff in [C++](markov.cpp)!
+
+#### Exercise 3-5
+The great strength of the STL is the ease with which one can experiment with different data structures.
+Modify the C++ version of Markov to use various structures to represent the prefix, suffix list, and state table.
+How does performance change for the different structures?
diff --git a/chapter-3/3.6-c++/markov.cpp b/chapter-3/3.6-c++/markov.cpp
@@ -6,7 +6,9 @@
 #include <vector>
 
 typedef std::deque<std::string> Prefix;
-std::map<Prefix, std::vector<std::string> > statetab;
+typedef std::vector<std::string> Suffixes;
+typedef std::map<Prefix, Suffixes> State;
+State statetab;
 
 enum
 {
@@ -59,7 +61,7 @@ void generate(int nwords)
     srand(time(NULL));
     for (int i = 0; i < nwords; i++)
     {
-        std::vector<std::string> &suf = statetab[prefix];
+        Suffixes &suf = statetab[prefix];
         const std::string &w = suf[rand() % suf.size()];
         if (w == NONWORD)
             break;