feat: Top K Frequent Elements #237

Author: donghyeon95

top-k-frequent-elements/donghyeon95.java

@@ -0,0 +1,29 @@
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+class Solution {
+	public int[] topKFrequent(int[] nums, int k) {
+		HashMap<Integer, Integer> hm = new HashMap<>();
+
+		for (int num: nums) {
+			hm.put(num, hm.getOrDefault(num, 0)+1);
+		}
+
+		List<Map.Entry<Integer, Integer>> list = new ArrayList<>(hm.entrySet());
+		list.sort(Map.Entry.comparingByValue(Collections.reverseOrder()));
+
+		int index = 1;
+		ArrayList<Integer> answer = new ArrayList<>();
+		for (Map.Entry<Integer, Integer> entry: list) {
+			if (index > k) break;
+			answer.add(entry.getKey());
+			index++;
+		}
+
+		return answer.stream().mapToInt(Integer::intValue).toArray();
+	}
+}
+