Design Patter 11: Subsets | Problem: Letter Case Permutations

11_letter_case_permutation.cpp

@@ -0,0 +1,26 @@
+/* Problem: https://leetcode.com/problems/letter-case-permutation/
+ */
+
+#include "lib_leetcode.h"
+#include <iostream>
+#include <string>
+#include <vector>
+
+std::vector<std::string> solution(const std::string input) {
+  std::vector<std::string> perms = {""};
+  for (const char c : input) {
+    for (std::size_t i = 0, upto = perms.size(); i < upto; i++) {
+      if (std::isalpha(c))
+        perms.push_back(perms[i] + (char)std::toupper(c));
+      perms[i] += std::tolower(c);
+    }
+  }
+  return perms;
+}
+
+int main() {
+  std::cout << solution("a1b2") << '\n'
+            << solution("3z4") << '\n'
+            << solution("mQe") << '\n'
+            << solution("03fH") << '\n';
+}

CMakeLists.txt

@@ -24,3 +24,5 @@ add_executable(8_binary_tree_level_order_traversal 8_binary_tree_level_order_tra
 add_executable(9_path_sum_iii 9_path_sum_iii.cpp)
 
 add_executable(10_find_the_median_of_a_number_stream 10_find_the_median_of_a_number_stream.cpp)
+
+add_executable(11_letter_case_permutation 11_letter_case_permutation.cpp)

lib_leetcode.h

@@ -6,6 +6,8 @@
 #include <iostream>
 #include <limits>
 #include <queue>
+#include <string>
+#include <typeinfo>
 #include <vector>
 
 /* Below TreeNode definition is copied from the problem at
@@ -58,9 +60,11 @@ std::ostream &operator<<(std::ostream &out, const std::vector<T> &vec) {
     out << "}";
     return out;
   }
-  for (int num : vec) {
+  for (T e : vec) {
-    std::cout << num << ", ";
+    std::cout << e << ", ";
   }
+  if (typeid(vec[0]) == typeid(std::string))
+    out << '\b';
   out << " \b\b}";
   return out;
 }
@@ -73,7 +77,7 @@ std::ostream &operator<<(std::ostream &out,
     out << "}";
     return out;
   }
-  for (const std::vector<int> &vec : vec_2d)
+  for (const std::vector<T> &vec : vec_2d)
     out << vec << ", ";
   out << " \b\b}";
   return out;