diff --git a/exercises/acronym/example.cpp b/exercises/acronym/example.cpp
index 0f7c607e..a92e40d4 100644
--- a/exercises/acronym/example.cpp
+++ b/exercises/acronym/example.cpp
@@ -1,23 +1,24 @@
-#include <vector>
-#include <boost/algorithm/string.hpp>
+#include <cctype>
 #include "acronym.h"
 
 using std::string;
-using std::vector;
 
 namespace acronym {
 
-string acronym(string const& input_str)
-{
-    vector<string> words;
-    boost::split(words, input_str, boost::is_any_of(" :-,"));
+string acronym(string const &input_str) {
     string acronym_str;
-    for (auto const& s : words) {
-        if (!s.empty()) {
-            acronym_str.push_back((boost::algorithm::to_upper_copy(s)).front());
+    string delimiters = " :-,";
+    enum DelimiterState { NOT_FOUND, FOUND };
+    DelimiterState delimiter_state = FOUND;
+    for (char c : input_str) {
+        if (delimiters.find(c) != string::npos) {
+            delimiter_state = FOUND;
+        } else if (delimiter_state == FOUND) {
+            delimiter_state = NOT_FOUND;
+            acronym_str.push_back(std::toupper(c));
         }
     }
     return acronym_str;
 }
 
-}
+}  // namespace acronym
diff --git a/exercises/anagram/example.cpp b/exercises/anagram/example.cpp
index dd7aa79e..ee753a20 100644
--- a/exercises/anagram/example.cpp
+++ b/exercises/anagram/example.cpp
@@ -1,5 +1,4 @@
 #include "anagram.h"
-#include <boost/algorithm/string/case_conv.hpp>
 #include <algorithm>
 #include <cctype>
 
@@ -8,9 +7,18 @@ using namespace std;
 namespace
 {
 
+string to_lower_copy(std::string const& s)
+{
+    string cpy(s);
+    for (auto& c: cpy) {
+        c = tolower(c);
+    }
+    return cpy;
+}
+
 string make_key(std::string const& s)
 {
-    string key{boost::to_lower_copy(s)};
+    string key{to_lower_copy(s)};
     sort(key.begin(), key.end());
     return key;
 }
@@ -31,7 +39,7 @@ vector<string> anagram::matches(vector<string> const& matches)
     vector<string> result;
     for (string const& s : matches) {
         if (s.length() == key_.length()
-                && boost::to_lower_copy(s) != boost::to_lower_copy(subject_)
+                && to_lower_copy(s) != to_lower_copy(subject_)
                 && make_key(s) == key_) {
             result.push_back(s);
         }
diff --git a/exercises/bob/example.cpp b/exercises/bob/example.cpp
index 293bf764..793f3e71 100644
--- a/exercises/bob/example.cpp
+++ b/exercises/bob/example.cpp
@@ -1,5 +1,4 @@
 #include "bob.h"
-#include <boost/algorithm/string/trim.hpp>
 #include <algorithm>
 #include <cctype>
 #include <iterator>
@@ -11,6 +10,18 @@ namespace bob
 namespace
 {
 
+string trim_copy(string const& s)
+{
+    string cpy(s);
+    // Trim front
+    while (!cpy.empty() && cpy.front() == ' ')
+        cpy.erase(cpy.begin());
+    // Trim back
+    while (!cpy.empty() && cpy.back() == ' ')
+        cpy.pop_back();
+    return cpy;
+}
+
 bool is_upper(string const& text)
 {
     auto last = end(text);
@@ -33,12 +44,12 @@ bool is_shouting(string const &text)
 
 bool is_question(string const &text)
 {
-    return boost::algorithm::trim_copy(text).back() == '?';
+    return trim_copy(text).back() == '?';
 }
 
 bool is_silence(string const& text)
 {
-    return boost::algorithm::trim_copy(text).length() == 0;
+    return trim_copy(text).length() == 0;
 }
 
 }
diff --git a/exercises/crypto-square/example.cpp b/exercises/crypto-square/example.cpp
index 78474a9c..4cf16e0b 100644
--- a/exercises/crypto-square/example.cpp
+++ b/exercises/crypto-square/example.cpp
@@ -1,5 +1,4 @@
 #include "crypto_square.h"
-#include <boost/algorithm/string/case_conv.hpp>
 #include <algorithm>
 #include <cctype>
 #include <iterator>
@@ -9,12 +8,21 @@ using namespace std;
 namespace
 {
 
+string to_lower_copy(std::string& s)
+{
+    string cpy(s);
+    for (auto& c: cpy) {
+        c = tolower(c);
+    }
+    return cpy;
+}
+
 string normalize(string const &text)
 {
     string result;
     copy_if(text.begin(), text.end(), back_inserter(result),
         [](const char c) { return !isspace(c) && !ispunct(c); });
-    return boost::to_lower_copy(result);
+    return to_lower_copy(result);
 }
 
 }
diff --git a/exercises/word-count/example.cpp b/exercises/word-count/example.cpp
index 1e9b762c..6753df34 100644
--- a/exercises/word-count/example.cpp
+++ b/exercises/word-count/example.cpp
@@ -3,13 +3,42 @@
 #include <cctype>
 #include <iterator>
 #include <vector>
-#include <boost/algorithm/string.hpp>
 
 using namespace std;
 
 namespace
 {
 
+string trim_copy_if(string const& s, string const& delims)
+{
+    string cpy(s);
+    // Trim front
+    while (!cpy.empty() && delims.find(cpy.front()) != string::npos)
+        cpy.erase(cpy.begin());
+    // Trim back
+    while (!cpy.empty() && delims.find(cpy.back()) != string::npos)
+        cpy.pop_back();
+    return cpy;
+}
+
+vector<string> split(string const& s, string const& delims)
+{
+    auto start = s.begin();
+    vector<string> words;
+    for (auto end = s.begin(); end != s.end(); end++) {
+        if (delims.find(*end) != string::npos) {
+            if (start != end) {
+                words.push_back(s.substr(start - s.begin(), end - start));
+            }
+            start = end + 1;
+        }
+    }
+    if (start < s.end()) {
+        words.push_back(s.substr(start - s.begin(), s.end() - start));
+    }
+    return words;
+}
+
 string normalize_text(string const& text)
 {
     string normalized;
@@ -20,13 +49,12 @@ string normalize_text(string const& text)
 
 string trim_word(string const& word)
 {
-    return boost::trim_copy_if(word, boost::is_any_of("' "));
+    return trim_copy_if(word, "' ");
 }
 
 vector<string> split_text_into_words(string const& text)
 {
-    vector<string> words;
-    boost::split(words, text, boost::is_any_of("\t "));
+    vector<string> words = split(text, "\t ");
     transform(words.begin(), words.end(), words.begin(), trim_word);
     return words;
 }