@@ -0,0 +1,51 @@
+package backjoon;
+// https://www.acmicpc.net/problem/18870
+// 좌표 압축
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.StringTokenizer;
+
+public class _18870 {
+  public static void main(String[] args) throws IOException {
+    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    // memory 359492 runtime 1696
+    int N = Integer.parseInt(br.readLine());
+    StringTokenizer st = new StringTokenizer(br.readLine(), " ");
+    int[] nums = new int[N];
+    for (int i = 0; i < N; i++){
+      nums[i] = Integer.parseInt(st.nextToken());
+    }
+
+    // 정렬
+    int[] sortNums = nums.clone();
+    Arrays.sort(sortNums);
+
+    // 중복되지 않는 좌표값과 idx저장
+    Map<Integer, Integer> map = new HashMap<>();
+    int idx = 0;
+    for(int n : sortNums){
+      if(!map.containsKey(n)){
+        map.put(n, idx++);
+      }
+    }
+    
+    // 출력
+    StringBuffer sb = new StringBuffer();
+    for(int n : nums){
+      sb.append(map.get(n)).append(" ");
+    }
+    System.out.println(sb);
+  }
+}
+/*
+input
+5
+2 4 -10 4 -9
+
+output
+2 3 0 3 1
+ */