write date and time related utils

test/utils_test.cpp

@@ -0,0 +1,25 @@
+#include "../src/include/utils.h"
+#include <cassert>
+#include <iostream>
+int main() {
+  int time_stamp = 0;
+  for (int i = 0; i <= 365; i++) {
+    std::pair<int, int> date = RetrieveReadableDate(i);
+    std::cout << i << " " << date.first << " " << date.second << std::endl;
+    assert(GetCompactDate(date.first, date.second) == i);
+    for (int j = 0; j < 1440; j++) {
+      int std_hour = j / 60;
+      int std_minute = j % 60;
+      int out_month, out_day, out_hour, out_minute;
+      assert(time_stamp == i * 1440 + j);
+      RetrieveReadableTimeStamp(time_stamp, out_month, out_day, out_hour, out_minute);
+      assert(out_month == date.first);
+      assert(out_day == date.second);
+      assert(out_minute == std_minute);
+      assert(out_hour == std_hour);
+      assert(GetFullTimeStamp(out_month, out_day, out_hour, out_minute) == time_stamp);
+      time_stamp++;
+    }
+  }
+  return 0;
+}