CP Reminder

An Android companion for competitive programmers. Tracks your daily CodeForres streak, lists upcoming contests, lets you favorite them and set custom reminders, and ranks a leaderboard of friends by rating.

Features

• Streak tracking — three-tier status (safe / warning / danger), cached display, daily alarms gated on "solved today."
• Contests — upcoming CodeForces contests, favorite with default 15-min lead time, add more per contest, confirmation dialogs on delete, reboot persistence.
• Friends leaderboard — add any handle, ranked by rating, self-row highlighted in green. Per-row icon shows if a friend has submitted an accepted solution today.
• Full-screen reminders — alarm ringtone + vibration over the lock screen, 10-minute snooze (suppressed if it would land past the day boundary / contest start).

Requirements

• Android 9 (API 28) or newer
• Internet permission (the app talks to the CodeForces API)
• SCHEDULE_EXACT_ALARM and POST_NOTIFICATIONS are also requested; grants for the latter are prompted for on Android 13+, the former is routed to the system settings screen on Android 12+.

Build

git clone https://github.com/0xPolybit/cp-reminder.git
cd cp-reminder
./gradlew assembleDebug

APK output: app/build/outputs/apk/debug/app-debug.apk. Install with adb install -r app/build/outputs/apk/debug/app-debug.apk.

Architecture

Single-activity, View-based Android app (no Compose, no RecyclerView).

• CodeForcesApi.kt — all CF API calls (verifyHandle, getProfile(s), getStreakStatus, hasAcceptedToday, getUpcomingContests). Shared httpGet and parseProfile helpers. One friend-fetch + mapNotNull per-handle error tolerance, so a single renamed handle can't fail the whole leaderboard.
• Alarm pipeline — AlarmScheduler for streak alarms (recurring daily before local midnight), ContestAlarmScheduler for one-time contest alarms. Both use AlarmManager.setAlarmClock and ensure their PendingIntent request codes are disjoint via a reserved bit. A shared AlarmReceiver branches on EXTRA_KIND; AlarmRingService is the foreground service, AlarmRingActivity is the full-screen ringing UI. For streak alarms, the receiver first checks CodeForcesApi.hasAcceptedToday via goAsync() and silently skips ringing if the user has already solved.
• Persistence — all prefs share one file (cp_reminder_prefs) with distinct keys per concern (alarms, contest_favorites, friends, streak_cache, cf_username). JSON-serialized via org.json.

Permissions

INTERNET, SCHEDULE_EXACT_ALARM, RECEIVE_BOOT_COMPLETED, WAKE_LOCK, VIBRATE, FOREGROUND_SERVICE, FOREGROUND_SERVICE_MEDIA_PLAYBACK, USE_FULL_SCREEN_INTENT, POST_NOTIFICATIONS.

License

MIT.content>