diff --git a/yitou/src/Main.java b/yitou/src/Main.java
new file mode 100644
index 0000000000000000000000000000000000000000..a0e8cb9b52142f8cdcbe14a0d02c038bb722d58f
--- /dev/null
+++ b/yitou/src/Main.java
@@ -0,0 +1,32 @@
+package src;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class Main {
+  public static void main(final String[] args) {
+    final Scanner scanner = new Scanner(System.in);
+
+    // 参加者数の取得
+    final int participantNum = scanner.nextInt();
+    final List<Participant> participantsList = new ArrayList<>();
+
+    // 各参加者の得点をリストに格納
+    for (int i = 0; i < participantNum; i++) {
+      final int score = scanner.nextInt();
+      participantsList.add(new Participant(score, i));
+    }
+    
+   scanner.close();
+
+    final RankingSystem rankingSystem = new RankingSystem(participantsList);
+    
+    rankingSystem.calculateRanks();
+
+    // 順位出力
+    for (Participant participant : rankingSystem.getParticipants()) {
+      System.out.println(participant.getRank());
+    }
+  }
+}
diff --git a/yitou/src/Participant.java b/yitou/src/Participant.java
new file mode 100644
index 0000000000000000000000000000000000000000..2cb15e81b5355401a2218163dc79c9ad0d827df8
--- /dev/null
+++ b/yitou/src/Participant.java
@@ -0,0 +1,28 @@
+package src;
+
+public class Participant {
+  private int score;
+  private int rank;
+  private int index;
+
+  public Participant(final int score, final int index) {
+    this.score = score;
+    this.index = index;
+  }
+
+  public int getScore() {
+    return score;
+  }
+
+  public int getRank() {
+    return rank;
+  }
+
+  public void setRank(final int rank) {
+    this.rank = rank;
+  }
+
+  public int getIndex() {
+    return index;
+  }
+}
diff --git a/yitou/src/RankingSystem.java b/yitou/src/RankingSystem.java
new file mode 100644
index 0000000000000000000000000000000000000000..18b30ffb2e5f5aab75490ba4c97bc2bb37ea4063
--- /dev/null
+++ b/yitou/src/RankingSystem.java
@@ -0,0 +1,44 @@
+package src;
+
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+public class RankingSystem {
+  private List<Participant> participants;
+
+  public RankingSystem(final List<Participant> participants) {
+    this.participants = participants;
+  }
+
+  public  void calculateRanks() {
+  //スコアを降順にソート
+  Collections.sort(participants, Comparator.comparing(Participant::getScore).reversed());
+
+
+
+  int currentRank = 1;
+  for (int number = 0; number < participants.size(); number++) {
+      if (number > 0 && isSameScore(number)) {
+          // 同点の場合は同じ順位
+          participants.get(number).setRank(participants.get(number - 1).getRank());
+      } else {
+          // 異なる場合は順位を設定
+          participants.get(number).setRank(currentRank);
+      }
+      currentRank++;
+  }
+    // 入力順で順位を再配置
+    Collections.sort(participants, Comparator.comparing(Participant::getIndex));
+  
+  }
+  
+  //引数indexの参加者のスコアが前の参加者と同じかどうか判定
+  private boolean isSameScore(int index) {
+    return participants.get(index).getScore() == participants.get(index - 1).getScore();
+  }
+
+  public List<Participant> getParticipants() {
+    return participants;
+  }
+}
diff --git a/yitou/test/RankingSystemTest.java b/yitou/test/RankingSystemTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..56ff5d339597daba521c050340b6cdf31e94e631
--- /dev/null
+++ b/yitou/test/RankingSystemTest.java
@@ -0,0 +1,60 @@
+package test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import src.Participant;
+import src.RankingSystem;
+
+public class RankingSystemTest {
+  private List<Participant> participants;
+  private RankingSystem rankingSystem;
+
+  @BeforeEach
+  public void setUp() {
+    participants = new ArrayList<>();
+    rankingSystem = new RankingSystem(participants);
+  }
+
+  @Test
+  public void スコアが異なる複数の参加者の場合() {
+    participants.add(new Participant(100, 0));
+    participants.add(new Participant(90, 1));
+    participants.add(new Participant(80, 2));
+    rankingSystem.calculateRanks();
+        
+    assertEquals(1, participants.get(0).getRank());
+    assertEquals(2, participants.get(1).getRank());
+    assertEquals(3, participants.get(2).getRank());
+  }
+
+  @Test
+  public void 同じスコアの参加者がいる場合() {
+    participants.add(new Participant(100, 0));
+    participants.add(new Participant(100, 1));
+    participants.add(new Participant(90, 2));
+    rankingSystem.calculateRanks();
+        
+    assertEquals(1, participants.get(0).getRank());
+    assertEquals(1, participants.get(1).getRank());
+    assertEquals(3, participants.get(2).getRank());
+  }
+
+  @Test
+  public void 同じスコアをもつ組み合わせが複数ある場合() {
+    participants.add(new Participant(100, 0));
+    participants.add(new Participant(90, 1));
+    participants.add(new Participant(100, 2));
+    participants.add(new Participant(90, 3));
+    participants.add(new Participant(80, 4));
+    rankingSystem.calculateRanks();
+        
+    assertEquals(1, participants.get(0).getRank());
+    assertEquals(3, participants.get(1).getRank());
+    assertEquals(1, participants.get(2).getRank());
+    assertEquals(3, participants.get(3).getRank());
+    assertEquals(5, participants.get(4).getRank());
+  }
+}