C++14 Day 8 solution

2016/c++14/08/main.cpp

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+// Advent of Code 2016 Day 8
+
+#include <iostream>
+#include <vector>
+#include <string>
+#include <utility>
+
+#include "screen.hpp"
+
+enum class Instr{ rect, rotate_col, rotate_row, invalid_instr };
+
+Instr getInstr(const std::string& line)
+{
+	if (line.find("rect") == 0) return Instr::rect;
+	if (line.find("column") != std::string::npos) return Instr::rotate_col;
+	if (line.find("row") != std::string::npos) return Instr::rotate_row;
+
+	// else say it's an invalid line
+	return Instr::invalid_instr;
+}
+
+std::pair<int, int> getParams(const std::string& line, Instr instrType)
+{
+	if (instrType == Instr::rect) {
+		// too lazy to type out std::string::size_type
+		auto instrEnd{line.find(' ')};
+		auto paramSeparator{line.find('x')};
+
+		std::string row{line.substr(instrEnd + 1, paramSeparator - instrEnd - 1)};
+		std::string col{line.substr(paramSeparator + 1, line.size() - paramSeparator)};
+
+		return std::pair<int, int>(std::stoi(row), std::stoi(col));
+
+	} else if (instrType == Instr::rotate_col || instrType == Instr::rotate_row) {
+		// too lazy to type out std::string::size_type
+		auto rowOrColBegin{line.find('=')};
+		auto amtBegin{line.find("by ")};
+
+
+		std::string rowOrCol{line.substr(rowOrColBegin + 1, amtBegin - rowOrColBegin - 2)};
+		std::string amt{line.substr(amtBegin + 3, line.size() - amtBegin + 3)};
+
+		return std::pair<int, int>(std::stoi(rowOrCol), std::stoi(amt));
+
+	} else {
+		return std::pair<int, int>(-1, -1); // should probably throw an exception but eh
+	}
+}
+
+void runInstr(Screen& s, Instr instrType, const std::pair<int, int>& params)
+{
+	if (instrType == Instr::rect) {
+		s.rect(params.first, params.second);
+	} else if (instrType == Instr::rotate_col) {
+		s.rotateCol(params.first, params.second);
+	} else if (instrType == Instr::rotate_row) {
+		s.rotateRow(params.first, params.second);
+	}
+}
+
+int main()
+{
+	Screen s;
+
+	std::string line;
+	while (std::getline(std::cin, line)) {
+		Instr instrType{getInstr(line)};
+		std::pair<int, int> params{getParams(line, instrType)};	
+
+		runInstr(s, instrType, params);
+	}
+
+	s.displayScreen();
+	std::cout << "Number of on pixels: " << s.numPixelsOn() << std::endl;
+
+	return 0;
+}

2016/c++14/08/screen.cpp

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+// Advent of Code 2016 Day 8
+
+#include "screen.hpp"
+
+#include <iostream>
+
+const int Screen::ROWLENGTH{50};
+const int Screen::COLLENGTH{6};
+
+Screen::Screen() : screen{}
+{
+	for (auto& row : screen) {
+		row = std::array<char, 50>();
+		for (auto& col : row) {
+			col = '.';
+		}
+	}
+}
+
+void Screen::rect(int cols, int rows)
+{
+	for (int i = 0; i < rows; ++i) {
+		for (int j = 0; j < cols; ++j) {
+			screen[i][j] = '#';
+		}
+	}
+}
+
+void Screen::rotateCol(int col, int amt)
+{
+	for (int i = 0; i < amt; ++i) {
+		for (int row = COLLENGTH - 1; row > 0; --row) {
+			char temp{screen[row][col]};
+			screen[row][col] = screen[row - 1][col];
+			screen[row - 1][col] = temp;
+		}
+	}
+}
+
+void Screen::rotateRow(int row, int amt)
+{
+	for (int i = 0; i < amt; ++i) {
+		for (int col = ROWLENGTH - 1; col > 0; --col) {
+			char temp{screen[row][col]};
+			screen[row][col] = screen[row][col - 1];
+			screen[row][col - 1] = temp;
+		}
+	}
+}
+
+int Screen::numPixelsOn()
+{
+	int count{0};
+	for (const auto& row : screen) {
+		for (const auto& pixel : row) {
+			if (pixel != '.') ++count;
+		}
+	}
+	return count;
+}
+
+void Screen::displayScreen()
+{
+	for (const auto& row : screen) {
+		for (const auto& pixel : row) {
+			std::cout << pixel;
+		}
+		std::cout << std::endl;
+	}
+}

2016/c++14/08/screen.hpp

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+// Advent of Code 2016 Day 8
+
+#include <array>
+
+class Screen {
+public:
+	Screen();
+	void rect(int cols, int rows);
+	void rotateCol(int col, int amt);
+	void rotateRow(int row, int amt);
+
+	void displayScreen();
+	int numPixelsOn();
+
+private:
+	static const int ROWLENGTH;
+	static const int COLLENGTH;
+	std::array<std::array<char, 50>, 6> screen;
+};