feat(Codewars): WIP onlinePlatform/codewars/4kyu/counting_change_combinations.cc

Author: htbkoo

src/onlinePlatform/codewars/4kyu/CMakeLists.txt

@@ -9,3 +9,13 @@ target_link_libraries(
         GTest::gtest_main
 )
 gtest_discover_tests(matrix_determinant_google_test)
+
+add_executable(
+        counting_change_combinations_google_test
+        counting_change_combinations_google_test.cc
+)
+target_link_libraries(
+        counting_change_combinations_google_test
+        GTest::gtest_main
+)
+gtest_discover_tests(counting_change_combinations_google_test)

src/onlinePlatform/codewars/4kyu/counting_change_combinations.cc

@@ -0,0 +1,27 @@
+// https://www.codewars.com/kata/5263a84ffcadb968b6000513/train/cpp
+
+#include <vector>
+#include <unordered_set>
+
+using namespace std;
+
+unsigned long long countChange(const unsigned int money, const std::vector<unsigned int>& coins) {
+    // your code here
+
+    // TODO: is there duplicates in coins?
+
+    std::unordered_set<unsigned int> uniqueCoins(begin(coins), end(coins));
+
+    std::vector<long long> counts(money + 1);
+    counts[0] = 1;
+    for (auto coin: uniqueCoins) {
+        std::vector<long long> prev(begin(counts), end(counts));
+        counts = std::vector<long long>(money + 1);
+
+        for (auto i = money; i >= coin; --i) {
+            counts[i] += prev[i - coin];
+        }
+    }
+
+    return counts[money];
+}

src/onlinePlatform/codewars/4kyu/counting_change_combinations_google_test.cc

@@ -0,0 +1,11 @@
+#include <gtest/gtest.h>
+#include <string>
+#include <vector>
+
+#include "counting_change_combinations.cc"
+
+TEST(CountingChangeCombinations, countChange_test) {
+    EXPECT_EQ(countChange(4, {1,2}), 3);
+
+    EXPECT_EQ(countChange(10, {5,2,3}), 4);
+}