grayscale-image-algo exercise

homework/grayscale-image/compression.cpp

@@ -0,0 +1,38 @@
+#include "compression.hpp"
+#include <algorithm>
+
+std::vector<std::pair<uint8_t, uint8_t>> compressGrayscale(std::array<std::array<uint8_t, width>, height>& bitimg) {
+    std::vector<std::pair<uint8_t, uint8_t>> compressed;
+
+    std::for_each(bitimg.begin(), bitimg.end(), [&compressed](auto& column) {
+        int count = 1;
+        std::for_each(std::next(column.begin()), column.end(), [&compressed, &count, &column](auto& pixel) {
+            int row = std::distance(column.begin(), &pixel);
+            if (pixel == column[row - 1]) {
+                count++;
+            } else {
+                compressed.push_back({column[row - 1], count});
+                count = 1;
+            }
+            if (row == column.size() - 1) {
+                compressed.push_back({pixel, count});
+            }
+        });
+    });
+
+    return compressed;
+}
+
+std::array<std::array<uint8_t, width>, height> decompressGrayscale(std::vector<std::pair<uint8_t, uint8_t>>& compressed) {
+    std::array<std::array<uint8_t, width>, height> decompressed;
+
+    int index = 0;
+    std::for_each(compressed.begin(), compressed.end(), [&decompressed, &index](const std::pair<uint8_t, uint8_t>& c) {
+        uint8_t value = c.first;
+        uint8_t count = c.second;
+        std::generate_n(&decompressed[index / height][index % height], count, [value]() { return value; });
+        index += count;
+    });
+
+    return decompressed;
+}

homework/grayscale-image/compression.hpp

@@ -0,0 +1,12 @@
+#pragma once
+#include <array>
+#include <cstdint>
+#include <iterator>
+#include <map>
+#include <vector>
+
+constexpr std::size_t width = 32;
+constexpr std::size_t height = 32;
+
+std::vector<std::pair<uint8_t, uint8_t>> compressGrayscale(std::array<std::array<uint8_t, width>, height>& bitimg);
+std::array<std::array<uint8_t, width>, height> decompressGrayscale(std::vector<std::pair<uint8_t, uint8_t>>& bitimg);

homework/grayscale-image/main.cpp

@@ -1,7 +1,10 @@
+#include <algorithm>
 #include <array>
+#include <cstdint>
 #include <forward_list>
+#include <iterator>
 
-// TODO: include
+#include "compression.hpp"
 
 std::array<std::array<uint8_t, 32>, 32> generateNinja() {
     return {

homework/grayscale-image/test.cpp

@@ -3,7 +3,7 @@
 #include <utility>  // for std::pair<>
 #include <vector>
 
-// TODO: include
+#include "compression.hpp"
 #include "gtest/gtest.h"
 
 void expectBitmap(const std::vector<std::pair<uint8_t, uint8_t>>& bitmap, size_t fraction) {