Merge pull request #200 from softeerbootcamp4th/fix/#199-faster-alg

fix/#199-faster-alg
softeerbootcamp4th · Aug 21, 2024 · c89d782 · c89d782
2 parents 9c9f82b + b9d2b07
commit c89d782
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Showing 3 changed files with 37 additions and 27 deletions.
diff --git a/...r/src/main/java/JGS/CasperEvent/domain/event/entity/participants/LotteryParticipants.java b/...r/src/main/java/JGS/CasperEvent/domain/event/entity/participants/LotteryParticipants.java
@@ -14,9 +14,8 @@ public class LotteryParticipants extends BaseEntity {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
-    @OneToOne // mappedBy 이용하면 둘 다 저장 안해도 됨
+    @OneToOne(fetch = FetchType.LAZY) // mappedBy 이용하면 둘 다 저장 안해도 됨
     @JoinColumn(name = "base_user_id")
-    //todo: 왜이런지 알아보기
     @JsonBackReference
     @JsonIgnore
     private BaseUser baseUser;

diff --git a/...erEvent/domain/event/repository/participantsRepository/LotteryParticipantsRepository.java b/...erEvent/domain/event/repository/participantsRepository/LotteryParticipantsRepository.java
@@ -9,6 +9,7 @@
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
+import java.util.List;
 import java.util.Optional;
 
 @Repository
@@ -20,5 +21,8 @@ public interface LotteryParticipantsRepository extends JpaRepository<LotteryPart
 
     @Query("SELECT COUNT(p) FROM LotteryParticipants p WHERE p.baseUser.id LIKE :id%")
     long countByBaseUser_Id(@Param("id") String id);
+
+    @Query("SELECT lp.id, lp.appliedCount From LotteryParticipants lp")
+    List<Object[]> findIdAndAppliedCounts();
 }
 
diff --git a/Server/src/main/java/JGS/CasperEvent/domain/event/service/adminService/AdminService.java b/Server/src/main/java/JGS/CasperEvent/domain/event/service/adminService/AdminService.java
@@ -68,7 +68,6 @@ public Admin verifyAdmin(AdminRequestDto adminRequestDto) {
     // 어드민 생성
     public ResponseDto postAdmin(AdminRequestDto adminRequestDto) {
         String adminId = adminRequestDto.getAdminId();
-        //Todo: 비밀번호 암호화 필요
         String password = adminRequestDto.getPassword();
 
         Admin admin = adminRepository.findById(adminId).orElse(null);
@@ -338,41 +337,49 @@ public ResponseDto pickLotteryEventWinners() {
 
         int winnerCount = lotteryEvent.getWinnerCount();
 
-        List<LotteryParticipants> lotteryParticipants = lotteryParticipantsRepository.findAll();
+        List<Object[]> lotteryParticipants = lotteryParticipantsRepository.findIdAndAppliedCounts();
 
-        if(winnerCount >= lotteryParticipants.size()){
-            for (LotteryParticipants lotteryParticipant : lotteryParticipants) {
-                lotteryWinnerRepository.save(new LotteryWinners(lotteryParticipant));
+        if (winnerCount >= lotteryParticipants.size()) {
+            for (Object[] lotteryParticipant : lotteryParticipants) {
+                lotteryWinnerRepository.save(new LotteryWinners(
+                        lotteryParticipantsRepository.findById((Long) lotteryParticipant[0]).get()
+                ));
             }
             return new ResponseDto("추첨이 완료되었습니다.");
         }
-        Set<LotteryParticipants> lotteryEventWinners = new HashSet<>();
 
-        int totalWeight;
-        Random random = new Random();
-        while (lotteryEventWinners.size() < winnerCount) {
-            totalWeight = 0;
-            for (LotteryParticipants lotteryParticipant : lotteryParticipants) {
-                totalWeight += lotteryParticipant.getAppliedCount();
-            }
+        int appliedCount;
+        List<Long> appliedParticipants = new ArrayList<>();
 
-            int randomValue = random.nextInt(totalWeight) + 1;
-
-            int cumulativeSum = 0;
-            for (LotteryParticipants lotteryParticipant : lotteryParticipants) {
-                cumulativeSum += lotteryParticipant.getAppliedCount();
-                if (randomValue <= cumulativeSum) {
-                    lotteryEventWinners.add(lotteryParticipant);
-                    lotteryParticipants.remove(lotteryParticipant);
-                    break;
-                }
+        for (Object[] lotteryParticipant : lotteryParticipants) {
+            appliedCount = (int) lotteryParticipant[1];
+            for (int i = 0; i < appliedCount; i++) {
+                appliedParticipants.add((long) lotteryParticipant[0]);
             }
         }
 
-        for (LotteryParticipants lotteryEventWinner : lotteryEventWinners) {
-            lotteryWinnerRepository.save(new LotteryWinners(lotteryEventWinner));
+        // Fisher-Yates Shuffle Algorithm
+        Random random = new Random();
+        for (int i = appliedParticipants.size() - 1; i > 0; i--) {
+            int j = random.nextInt(i + 1);
+            Long temp = appliedParticipants.get(i);
+            appliedParticipants.set(i, appliedParticipants.get(j));
+            appliedParticipants.set(j, temp);
         }
 
+        Set<Long> lotteryEventWinners = new HashSet<>();
+        while (lotteryEventWinners.size() < winnerCount) {
+            Long winnerId = appliedParticipants.remove(0);
+            if (lotteryEventWinners.contains(winnerId)) continue;
+            lotteryEventWinners.add(winnerId);
+        }
+
+        List<LotteryWinners> winnersToSave = lotteryEventWinners.stream()
+                .map(winnerId -> new LotteryWinners(lotteryParticipantsRepository.findById(winnerId).get()))
+                .collect(Collectors.toList());
+
+        lotteryWinnerRepository.saveAll(winnersToSave);
+
         return new ResponseDto("추첨이 완료되었습니다.");
     }