Minimum Recolors to Get K Consecutive Black Blocks

CMakeLists.txt

@@ -428,6 +428,7 @@ add_task(minimum-operations-to-collect-elements)
 add_task(minimum-operations-to-reduce-x-to-zero)
 add_task(minimum-path-sum)
 add_task(minimum-penalty-for-a-shop)
+add_task(minimum-recolors-to-get-k-consecutive-black-blocks)
 add_task(minimum-remove-to-make-valid-parentheses)
 add_task(minimum-replacements-to-sort-the-array)
 add_task(minimum-right-shifts-to-sort-the-array)

solutions/minimum-recolors-to-get-k-consecutive-black-blocks/CMakeLists.txt

@@ -0,0 +1 @@
+add_catch(test_minimum_recolors_to_get_k_consecutive_black_blocks test.cpp)

solutions/minimum-recolors-to-get-k-consecutive-black-blocks/solution.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <string>
+
+class Solution {
+public:
+  static int minimumRecolors(std::string blocks, int k) {
+    const int n = blocks.size();
+    int cnt = 0, max = 0;
+    for (int i = 0; i < n; ++i) {
+      if (blocks[i] == 'B') {
+        ++cnt;
+      }
+      if (i >= k && blocks[i - k] == 'B') {
+        --cnt;
+      }
+      max = std::max(max, cnt);
+    }
+    return k - max;
+  }
+};

solutions/minimum-recolors-to-get-k-consecutive-black-blocks/test.cpp

@@ -0,0 +1,29 @@
+#include <catch.hpp>
+
+#include <solution.hpp>
+
+TEST_CASE("Simple") {
+  struct TestCase {
+    std::string blocks;
+    int k;
+    int expected;
+  };
+
+  std::vector<TestCase> test_cases{
+      {
+          .blocks = "WBBWWBBWBW",
+          .k = 7,
+          .expected = 3,
+      },
+      {
+          .blocks = "WBWBBBW",
+          .k = 2,
+          .expected = 0,
+      },
+  };
+
+  for (const auto &[blocks, k, expected] : test_cases) {
+    const auto actual = Solution::minimumRecolors(blocks, k);
+    REQUIRE(expected == actual);
+  }
+}