feat: top-k-frequent-elements solution

Author: sm9171

top-k-frequent-elements/sm9171.java

@@ -0,0 +1,27 @@
+class Solution {
+    public int[] topKFrequent(int[] nums, int k) {
+        Map<Integer, Integer> hashMap = new HashMap<>();
+        for (int i = 0; i < nums.length; i++) {
+            int num = nums[i];
+            if (hashMap.containsKey(num)) {
+                hashMap.put(num, hashMap.get(num) + 1);
+                continue;
+            }
+            hashMap.put(num, 1);
+        }
+
+        List<Integer> list = hashMap.entrySet()
+                .stream()
+                .sorted(Map.Entry.<Integer, Integer>comparingByValue().reversed())
+                .limit(k)
+                .map(Map.Entry::getKey)
+                .toList();
+
+        int [] result = new int[list.size()];
+        for (int i = 0; i < list.size(); i++) {
+            result[i] = list.get(i);
+        }
+
+        return result;
+    }
+}