k most occurred using bucket method

Author: joharbatta

HashMap/kmostOccured.java

@@ -0,0 +1,58 @@
+//Find Top K Most Frequent Numbers in an Array
+
+public class kmostOccured {
+ 
+   public static List<Integer> kMostFrequent(int[] nums, int k) {
+ 
+ 
+      Map<Integer, Integer> countMap = new HashMap<>();
+
+      int maxFreq = 0;
+ 
+
+      for(int i = 0; i < nums.length; i++) {
+       
+  
+        int freq = countMap.getOrDefault(nums[i],0)+1;         
+ 
+        countMap.put(nums[i], freq);  
+        
+        maxFreq = Math.max(maxFreq, freq);            
+      }
+ 
+      List<Integer>[] bucket = new List[maxFreq + 1];
+ 
+      for(int n : countMap.keySet()) 
+      {
+        int freq = countMap.get(n);
+ 
+        if(bucket[freq]==null)
+          bucket[freq] = new ArrayList<>();
+ 
+        bucket[freq].add(n);
+      }
+ 
+      List<Integer> res = new ArrayList<>();
+ 
+      for(int i = bucket.length-1; i >= 0 && k>0; i--) 
+      { 
+          if(bucket[i]!=null)
+          {
+             List<Integer> list = bucket[i]; 
+             res.addAll(list);
+             k-= list.size();
+          }
+       }
+    
+      return res;
+  }
+ 
+  public static void main(String[] args) {
+       int[] arr = {1, 1, 1, 2, 2, 3, 3, 3};
+       List<Integer> result = kMostFrequent(arr, 2);
+ 
+       for(Integer elem : result) {
+         System.out.print(elem + " ");
+       }
+  }
+}