From 77c36f8e104a9c2e4fab666a763d444cf556732c Mon Sep 17 00:00:00 2001
From: Dmitry Kokorin <dmitry@kokorin.org>
Date: Sun, 6 Mar 2016 19:38:58 +0300
Subject: [PATCH] robot_name: rand() -> c++11 random

---
 cpp/robot-name/robot_name.cpp | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/cpp/robot-name/robot_name.cpp b/cpp/robot-name/robot_name.cpp
index a22660a..5b79010 100644
--- a/cpp/robot-name/robot_name.cpp
+++ b/cpp/robot-name/robot_name.cpp
@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <set>
+#include <random>
 
 
 namespace robot_name {
@@ -11,14 +12,18 @@ using namespace std;
 
 namespace {
 
+typedef uniform_int_distribution<char> distribution_t;
+
 const size_t alpha_part_size = 2;
 const size_t digit_part_size = 3;
 
 
-string random_string(size_t size, char from_char, char to_char)
+string random_string(size_t size, distribution_t &distribution)
 {
-    auto random_char = [from_char, to_char]() -> char {
-        return from_char + rand() % (to_char - from_char + 1);
+    static default_random_engine engine;
+
+    auto random_char = [&distribution]() -> char {
+        return distribution(engine);
     };
 
     string result(size, 0);
@@ -40,12 +45,16 @@ void robot::reset()
     static set<name_t>  used_names;
     static const size_t name_capacity = pow('Z' - 'A' + 1, alpha_part_size)
                                       * pow('9' - '0' + 1, digit_part_size);
+
+    static distribution_t alpha_distribution('A', 'Z');
+    static distribution_t digit_distribution('0', '9');
+
     string new_name;
 
     do {
 
-        new_name = random_string(alpha_part_size, 'A', 'Z')
-                 + random_string(digit_part_size, '0', '9');
+        new_name = random_string(alpha_part_size, alpha_distribution)
+                 + random_string(digit_part_size, digit_distribution);
 
     } while (used_names.size() < name_capacity && used_names.count(new_name));