[BOJ] 2910 빈도 정렬 (S3)

Author: abcxj123

정건우/9주차/260225.java

@@ -0,0 +1,51 @@
+//https://www.acmicpc.net/problem/2910
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+public class BOJ_S3_2910_빈도정렬 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int N = Integer.parseInt(st.nextToken());
+        int C = Integer.parseInt(st.nextToken());
+
+        Map<Integer, Integer> indexMap = new HashMap<>();
+        Map<Integer, Integer> countMap = new HashMap<>();
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            int n = Integer.parseInt(st.nextToken());
+
+            if(!indexMap.containsKey(n)) {
+                indexMap.put(n, i);
+                countMap.put(n, 0);
+            }
+
+            countMap.put(n, countMap.get(n) + 1);
+        }
+
+        List<Integer> list = new ArrayList<>(indexMap.keySet());
+        Collections.sort(list, (o1, o2) -> {
+            if(countMap.get(o1) != countMap.get(o2)) {
+                return countMap.get(o2) - countMap.get(o1);
+            } else {
+                return indexMap.get(o1) - indexMap.get(o2);
+            }
+        });
+
+        StringBuilder sb = new StringBuilder();
+
+        for (int n : list) {
+            for (int i = 0; i < countMap.get(n); i++) {
+                sb.append(n).append(' ');
+            }
+        }
+
+        sb.setLength(sb.length()-1);
+        System.out.println(sb.toString());
+
+    }
+}