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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		// Test getMostPopularItem method
  13. 		List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 6, 6, 1, 1, 1);
  14.         int mostPopularItem = getMostPopularItem(list);
  15.         System.out.println("Most popular item: " + mostPopularItem);
  16. 	}
  17.  
  18. 	public static <T> T getMostPopularItem(Iterable<T> collection) {
  19.         // Create new map that will hold pairs:
  20.         // (item) -> (number of it's occurence in collection)
  21.         Map<T, Integer> map = new HashMap<>();
  22.  
  23.         T mostPopularItem = null;
  24.         int maxNumOfOccurence = 0;
  25.         for (T item : collection) {
  26.             // Add item to map
  27.             Integer numOfOccur = 1;
  28.             Integer prevNumOfOccur = map.put(item, numOfOccur);
  29.             // Correct number of occurence if it's not first time it's added
  30.             if (prevNumOfOccur != null) {
  31.                 numOfOccur = map.put(item, prevNumOfOccur + numOfOccur);
  32.             }
  33.             // Correct mostPopularItem
  34.             if (numOfOccur > maxNumOfOccurence) {
  35.                 mostPopularItem = item;
  36.             }
  37.         }
  38.  
  39.         return mostPopularItem;
  40.     }
  41. }
Success #stdin #stdout 0.04s 2184192KB
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Standard input is empty
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Most popular item: 1
https://ideone.com/RBPcqr
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
public

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