first three days

day3/src/main.cpp

@@ -0,0 +1,90 @@
+#include <cmath>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <numeric>
+#include <vector>
+
+int do_part_1(const std::string &line) {
+  int greatest = -1;
+  int second_greatest = -1;
+  for (size_t i = 0; i < line.length(); i++) {
+    char c = line[i];
+    int j = static_cast<int>(c - '0');
+    if (j > greatest && i < (line.length() - 1)) {
+      second_greatest = -1;
+      greatest = j;
+    } else if (j > second_greatest) {
+      second_greatest = j;
+    }
+  }
+
+  auto joint = std::to_string(greatest) + std::to_string(second_greatest);
+
+  return std::stoi(joint);
+}
+
+int find_highest_leading(std::string &line, int len) {
+  int highest_leading = -1;
+  int highest_pos = -1;
+  for (size_t i = 0; i < (line.length() - len + 1); i++) {
+    int j = static_cast<int>(line[i] - '0');
+    if (j > highest_leading) {
+      highest_leading = j;
+      highest_pos = i;
+    }
+  }
+  line = line.substr(highest_pos + 1);
+  return highest_leading;
+}
+
+long do_part_2(std::string line) {
+  std::string highest_seq = "";
+  for (int i = 12; i > 0; i--) {
+    std::cout << "line " << line << std::endl;
+    int highest_leading = find_highest_leading(line, i);
+    highest_seq += std::to_string(highest_leading);
+  }
+  return std::stol(highest_seq);
+}
+
+std::tuple<long, long> parse_input_file(const std::string &path) {
+  std::ifstream file;
+  std::string line;
+
+  file.open(path);
+  long part_1 = 0;
+  long part_2 = 0;
+  std::vector<int> part1_ints;
+  std::vector<long> part2_longs;
+  if (file.is_open()) {
+    std::getline(file, line);
+    while (!line.empty()) {
+      part_1 = do_part_1(line);
+      part1_ints.emplace_back(part_1);
+      part_2 = do_part_2(line);
+      part2_longs.emplace_back(part_2);
+      std::getline(file, line);
+    }
+  } else {
+    std::cerr << "Error opening file: " << path << std::endl;
+    return {0, 0};
+  }
+
+  part_1 = std::accumulate(part1_ints.begin(), part1_ints.end(), 0L);
+  part_2 = std::accumulate(part2_longs.begin(), part2_longs.end(), 0L);
+
+  return {part_1, part_2};
+}
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    std::cout << "One argument required: input txt" << std::endl;
+  }
+
+  auto results = parse_input_file(argv[1]);
+  std::cout << "Part 1: " << std::get<0>(results) << std::endl;
+  std::cout << "Part 2: " << std::get<1>(results) << std::endl;
+
+  return 0;
+}