Move c++ solutions into separate directory

2024/cpp/day-04/main.cpp

@@ -0,0 +1,97 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+vector<string> readInput()
+{
+    vector<string> lines;
+    string line;
+    while (getline(cin, line)) {
+        lines.push_back(line);
+    }
+    return lines;
+}
+
+bool wordIsXmas(const string &word)
+{
+    return word == "XMAS" || word == "SAMX";
+}
+
+bool wordIsMas(const string &word)
+{
+    return word == "MAS" || word == "SAM";
+}
+
+int xmasCountAt(const vector<string> &matrix, const size_t rowIndex, const size_t colIndex)
+{
+    const size_t numberOfRows = matrix.size();
+    const size_t numberOfCols = matrix[0].size();
+
+    int xmasCount = 0;
+
+    if (colIndex + 3 < numberOfCols) {
+        string horizontalWord = matrix[rowIndex].substr(colIndex, 4);
+        xmasCount += wordIsXmas(horizontalWord);
+    }
+
+    if (rowIndex + 3 < numberOfRows) {
+        string verticalWord;
+        for (size_t i = 0; i <= 3; i++) {
+            verticalWord += matrix[rowIndex + i][colIndex];
+        }
+        xmasCount += wordIsXmas(verticalWord);
+    }
+
+    if (rowIndex + 3 < numberOfRows && colIndex + 3 < numberOfCols) {
+        string downDiagonalWord, upDiagonalWord;
+        for (size_t i = 0; i <= 3; i++) {
+            downDiagonalWord += matrix[rowIndex + i][colIndex + i];
+            upDiagonalWord += matrix[rowIndex + (3 - i)][colIndex + i];
+        }
+        xmasCount += wordIsXmas(downDiagonalWord) + wordIsXmas(upDiagonalWord);
+    }
+
+    return xmasCount;
+}
+
+bool crossMasExistsAt(const vector<string> &matrix, const size_t rowIndex, const size_t colIndex)
+{
+    const size_t numberOfRows = matrix.size();
+    const size_t numberOfCols = matrix[0].size();
+
+    if (rowIndex + 2 >= numberOfRows || colIndex + 2 >= numberOfCols) {
+        return false;
+    }
+
+    string downDiagonalWord, upDiagonalWord;
+    for (size_t i = 0; i <= 2; i++) {
+        downDiagonalWord += matrix[rowIndex + i][colIndex + i];
+        upDiagonalWord += matrix[rowIndex + (2 - i)][colIndex + i];
+    }
+
+    return wordIsMas(downDiagonalWord) && wordIsMas(upDiagonalWord);
+}
+
+int main()
+{
+    const vector<string> matrix = readInput();
+    const size_t numberOfRows = matrix.size();
+    const size_t numberOfCols = matrix[0].size();
+
+    int numberOfXmasOccurrences = 0;
+    int numberOfCrossMasOccurrences = 0;
+
+    for (size_t rowIndex = 0; rowIndex < numberOfRows; rowIndex++) {
+        for (size_t colIndex = 0; colIndex < numberOfCols; colIndex++) {
+            numberOfXmasOccurrences += xmasCountAt(matrix, rowIndex, colIndex);
+            numberOfCrossMasOccurrences += crossMasExistsAt(matrix, rowIndex, colIndex);
+        }
+    }
+
+    // Part one
+    cout << "Number of XMAS occurrences: " << numberOfXmasOccurrences << endl;
+
+    // Part two
+    cout << "Number of X-MAS occurrences: " << numberOfCrossMasOccurrences << endl;
+}