From a86e0e294db3019b8104c5a93506e2f08bc54a58 Mon Sep 17 00:00:00 2001
From: Yuri Gorshenin <y@maps.me>
Date: Fri, 30 Jun 2017 20:30:56 +0300
Subject: [PATCH] Review fixes.

---
 base/base_tests/bwt_tests.cpp | 23 +++++++++++++++++++++++
 base/bwt.cpp                  |  1 +
 base/suffix_array.cpp         |  6 ++++--
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/base/base_tests/bwt_tests.cpp b/base/base_tests/bwt_tests.cpp
index 2338da3cc2..3a5d4c2fbb 100644
--- a/base/base_tests/bwt_tests.cpp
+++ b/base/base_tests/bwt_tests.cpp
@@ -3,6 +3,7 @@
 #include "base/bwt.hpp"
 
 #include <algorithm>
+#include <random>
 #include <string>
 
 using namespace base;
@@ -64,4 +65,26 @@ UNIT_TEST(RevBWT_Smoke)
     TEST_EQUAL(s, RevRevBWT(s), ());
   }
 }
+
+UNIT_TEST(RevBWT_AllBytes)
+{
+  int kSeed = 42;
+  int kMin = 1;
+  int kMax = 10;
+
+  mt19937 engine(kSeed);
+  uniform_int_distribution<int> uid(kMin, kMax);
+
+  string s;
+  for (size_t i = 0; i < 256; ++i)
+  {
+    auto const count = uid(engine);
+    ASSERT_GREATER_OR_EQUAL(count, kMin, ());
+    ASSERT_LESS_OR_EQUAL(count, kMax, ());
+    for (int j = 0; j < count; ++j)
+      s.push_back(static_cast<uint8_t>(i));
+  }
+  shuffle(s.begin(), s.end(), engine);
+  TEST_EQUAL(s, RevRevBWT(s), ());
+}
 }  // namespace
diff --git a/base/bwt.cpp b/base/bwt.cpp
index c416f673ad..0e56763adc 100644
--- a/base/bwt.cpp
+++ b/base/bwt.cpp
@@ -29,6 +29,7 @@ class FirstColumn
 public:
   FirstColumn(size_t n, uint8_t const * s) : m_n(n), m_starts({})
   {
+    m_starts.fill(0);
     for (size_t i = 0; i < n; ++i)
       ++m_starts[s[i]];
 
diff --git a/base/suffix_array.cpp b/base/suffix_array.cpp
index 7e5f5355ea..d77a473f78 100644
--- a/base/suffix_array.cpp
+++ b/base/suffix_array.cpp
@@ -60,6 +60,8 @@ struct SkewWrapper
     return 0;
   }
 
+  size_t MaxValue() const { return static_cast<size_t>(numeric_limits<uint8_t>::max()) + 1; }
+
   size_t const m_n;
   uint8_t const * const m_s;
 };
@@ -241,8 +243,8 @@ namespace base
 {
 void Skew(size_t n, uint8_t const * s, size_t * sa)
 {
-  auto const maxValue = static_cast<size_t>(numeric_limits<uint8_t>::max());
-  RawSkew(n, maxValue, SkewWrapper(n, s), sa);
+  SkewWrapper wrapper(n, s);
+  RawSkew(n, wrapper.MaxValue(), wrapper, sa);
 }
 
 void Skew(string const & s, vector<size_t> & sa)