Created
June 11, 2014 17:06
Top N Strings by quantity from input list of strings
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import java.util.*; | |
public class GetTop{ | |
public static void main(String[] args){ | |
List<String> input = new ArrayList<>(); | |
input.add("one"); | |
input.add("two"); | |
input.add("two"); | |
input.add("three"); | |
input.add("three"); | |
input.add("three"); | |
input.add("four"); | |
input.add("four"); | |
input.add("four"); | |
input.add("four"); | |
input.add("5"); | |
input.add("5"); | |
input.add("5"); | |
input.add("5"); | |
input.add("5"); | |
System.out.println(new GetTop().getTopThree(input, 3)); | |
} | |
public List<String> getTopThree(List<String> input, Integer topAmount){ | |
Map<String, Integer> stringCounts = new HashMap<>(); | |
for(String current: input){ | |
if(stringCounts.get(current)==null){ | |
stringCounts.put(current, 1); | |
}else{ | |
Integer newValue = stringCounts.get(current); | |
stringCounts.put(current, ++newValue); | |
} | |
} | |
NavigableMap<Integer, List<String>> result = new TreeMap<>(); | |
for(Map.Entry<String, Integer> entry: stringCounts.entrySet()){ | |
Integer count = entry.getValue(); | |
if(result.get(count)==null){ | |
List<String> resultList = new ArrayList<>(); | |
resultList.add(entry.getKey()); | |
result.put(count, resultList); | |
}else{ | |
result.get(count).add(entry.getKey()); | |
} | |
} | |
List<String> returned = new ArrayList<>(); | |
int j = returned.size(); | |
while(!result.isEmpty() && j < topAmount){ | |
Map.Entry<Integer, List<String>> entry = result.pollLastEntry(); | |
List<String> tempList = entry.getValue(); | |
for (int i = 0; i < tempList.size() && j < topAmount; i++){ | |
returned.add(tempList.get(i)); | |
j = returned.size(); | |
} | |
} | |
return returned; | |
} | |
} |
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