[LeetCode]Shortest Word Distance II

public class WordDistance {
    private HashMap<String, List<Integer>> map = new HashMap<String, List<Integer>>();
    public WordDistance(String[] words) {
        for (int i = 0; i < words.length; i++) {
            List<Integer> list = map.containsKey(words[i]) ? map.get(words[i]) : new ArrayList<Integer>();
            list.add(i);
            map.put(words[i], list);
        }
    }

    public int shortest(String word1, String word2) {
        List<Integer> list1 = map.get(word1);
        List<Integer> list2 = map.get(word2);
        int result = Integer.MAX_VALUE;
        int p1 = 0;
        int p2 = 0;
        int size1 = list1.size();
        int size2 = list2.size();
        while (p1 < size1 && p2 < size2) {
            result = Math.min(result, Math.abs(list1.get(p1) - list2.get(p2)));
            if (list1.get(p1) > list2.get(p2)) {
                p2 ++;
            } else {
                p1 ++;
            }
        }
        return result;
    }
}

// Your WordDistance object will be instantiated and called as such:
// WordDistance wordDistance = new WordDistance(words);
// wordDistance.shortest("word1", "word2");
// wordDistance.shortest("anotherWord1", "anotherWord2");