top-k-frequent-elements solution

Author: mintheon

top-k-frequent-elements/mintheon.java

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+import java.util.HashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.PriorityQueue;
+
+class Solution {
+  public int[] topKFrequent(int[] nums, int k) {
+    int[] answer = new int[k];
+    Map<Integer, Integer> frequent = new HashMap<>();
+
+    for(int num: nums) {
+      frequent.put(num, frequent.getOrDefault(num, 1) + 1);
+    }
+
+    PriorityQueue<Entry<Integer, Integer>> pq = new PriorityQueue<>((a, b) -> b.getValue().compareTo(a.getValue()));
+    pq.addAll(frequent.entrySet());
+
+    for(int i = 0; i < k; i++) {
+      answer[i] = pq.poll().getKey();
+    }
+
+    return answer;
+  }
+}