From b9d382731b7e148a13e10c974772c94650520579 Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Sat, 3 Sep 2022 23:52:07 +0200
Subject: [PATCH] =?UTF-8?q?problems(cpp):=20add=20=E2=80=9E967.=20Numbers?=
 =?UTF-8?q?=20With=20Same=20Consecutive=20Differences=E2=80=9C?=
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Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 ...bers-with-same-consecutive-differences.cpp | 74 +++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 problems/numbers-with-same-consecutive-differences.cpp

diff --git a/problems/numbers-with-same-consecutive-differences.cpp b/problems/numbers-with-same-consecutive-differences.cpp
new file mode 100644
index 0000000..dfdb7b4
--- /dev/null
+++ b/problems/numbers-with-same-consecutive-differences.cpp
@@ -0,0 +1,74 @@
+#include <vector>
+
+namespace {
+
+void nums_same_consec_diff(int n, int k, std::vector<int>& nums, int number)
+{
+    if (n == 0) {
+        nums.push_back(number);
+        return;
+    }
+
+    auto last_digit = number % 10;
+    for (int d = 0; d < 10; d++) {
+        if (std::abs(last_digit - d) == k) {
+            nums_same_consec_diff(n - 1, k, nums, number * 10 + d);
+        }
+    }
+}
+
+}
+
+class Solution {
+public:
+    std::vector<int> numsSameConsecDiff(int n, int k)
+    {
+        std::vector<int> nums;
+
+        for (int d = 1; d < 10; d++) {
+            nums_same_consec_diff(n - 1, k, nums, d);
+        }
+
+        return nums;
+    }
+};
+
+#pragma region tests
+
+#include <gtest/gtest.h>
+
+TEST(examples, first)
+{
+    Solution s;
+    ASSERT_EQ(s.numsSameConsecDiff(3, 7), (std::vector { 181, 292, 707, 818, 929 }));
+}
+
+TEST(examples, second)
+{
+    Solution s;
+    ASSERT_EQ(s.numsSameConsecDiff(2, 1),
+        (std::vector { 10, 12, 21, 23, 32, 34, 43, 45, 54, 56, 65, 67, 76, 78,
+            87, 89, 98 }));
+}
+
+TEST(same, two)
+{
+    Solution s;
+    ASSERT_EQ(s.numsSameConsecDiff(2, 0),
+        (std::vector { 11, 22, 33, 44, 55, 66, 77, 88, 99 }));
+}
+
+TEST(same, three)
+{
+    Solution s;
+    ASSERT_EQ(s.numsSameConsecDiff(3, 0),
+        (std::vector { 111, 222, 333, 444, 555, 666, 777, 888, 999 }));
+}
+
+int main(int argc, char** argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
+
+#pragma endregion /* tests */