ERD

ERD

테이블 관계

User ──┬── 1:N ──→ Submission (userId)
       └── 1:N ──→ Battle (winnerId, playerIds)

Problem ──┬── 1:N ──→ Battle (problemId)
          └── 1:N ──→ Submission (problemId)

Battle ── 1:N ──→ Submission (battleId)