Initial commit

2020/puzzle-13-01.cc

@@ -0,0 +1,52 @@
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <climits>
+#include <iostream>
+#include <list>
+#include <map>
+#include <regex>
+#include <string>
+
+using Time = unsigned long;
+
+int main(int argc, char **argv) {
+  Time arrival;
+  Time closest = ULONG_MAX;
+  Time closest_id = 0;
+  std::string line;
+  std::getline(std::cin, line);
+  arrival = std::stoul(line);
+  std::cout << "Arrival time: " << arrival << "\n";
+
+  std::string buses;
+  std::getline(std::cin, buses);
+  std::string::size_type pos = 0;
+
+  while (pos < buses.size()) {
+    if (buses[pos] == ',' || buses[pos] == 'x') {
+      ++pos;
+      continue;
+    }
+
+    std::string::size_type len = 0;
+    Time depart = std::stoul(buses.substr(pos), &len);
+    pos += len;
+    auto next_departure_in = depart - (arrival % depart);
+    if (next_departure_in == depart) {
+      next_departure_in = 0;
+    }
+    std::cout << "Bus #" << depart
+              << " previous departure: " << (arrival / depart) * depart
+              << ", next departure in: " << next_departure_in << "\n";
+    if (next_departure_in < closest) {
+      closest = next_departure_in;
+      closest_id = depart;
+    }
+  }
+
+  std::cout << "Next departure # " << closest_id << " in " << closest
+            << " minutes.\n";
+  std::cout << "Result = " << closest * closest_id << "\n";
+  return 0;
+}