g0601_0700.s0692_top_k_frequent_words.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

There is a newer version: 1.37

package g0601_0700.s0692_top_k_frequent_words;

// #Medium #String #Hash_Table #Sorting #Heap_Priority_Queue #Counting #Trie #Bucket_Sort

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;

public class Solution {
    /*
     * O(n) extra space
     * O(nlogk) time
     */
    public List topKFrequent(String[] words, int k) {
        Map map = new HashMap<>();
        for (String word : words) {
            map.put(word, map.getOrDefault(word, 0) + 1);
        }
        SortedSet> sortedset =
                new TreeSet<>(
                        (e1, e2) -> {
                            if (e1.getValue().intValue() != e2.getValue().intValue()) {
                                return e2.getValue() - e1.getValue();
                            } else {
                                return e1.getKey().compareToIgnoreCase(e2.getKey());
                            }
                        });
        sortedset.addAll(map.entrySet());
        List result = new ArrayList<>();
        Iterator> iterator = sortedset.iterator();
        while (iterator.hasNext() && k-- > 0) {
            result.add(iterator.next().getKey());
        }
        return result;
    }
}