top-k-frequent-elements

Author: chjung99

top-k-frequent-elements/chjung99.java

@@ -0,0 +1,34 @@
+class Solution {
+    public int[] topKFrequent(int[] nums, int k) {
+        Map<Integer, Integer> map = new HashMap<>();
+        int[] answer = new int[k];
+        int n = nums.length;
+        List<Data> result = new ArrayList<>();
+
+        for (int i = 0; i < n; i++) {
+            int key = nums[i];
+            if (map.get(key) == null) {
+                map.put(key, 1);
+            } else {
+                map.put(key, map.get(key) + 1);
+            }
+        }
+        for (int key: map.keySet()) {
+            result.add(new Data(key, map.get(key)));
+        }
+        result.sort((a, b) -> b.count() - a.count());
+
+        for (int i = 0; i < k; i++) {
+            answer[i] = result.get(i).key();
+        }
+
+        return answer;
+
+    }
+    record Data(
+            int key,
+            int count
+    ){}
+}
+
+