This is a follow up of Shortest Word Distance. The only difference is now you are given the list of words and your method will be called repeatedly many times with different parameters. How would you optimize it?
Design a class which receives a list of words in the constructor, and implements a method that takes two words word1 and word2 and return the shortest distance between these two words in the list.
For example,
Assume that words = ["practice", "makes", "perfect", "coding", "makes"].
Given word1 = “coding”, word2 = “practice”, return 3.
Given word1 = "makes", word2 = "coding", return 1.
Note:
You may assume that word1 does not equal to word2, and word1 and word2 are both in the list.
此题和Shortest Word Distance不同之处在于，此题要进行多次查找操作，而不是一次。用hashmap来做，代码如下：
public class WordDistance {
Map<String, List<Integer>> map = new HashMap<>();
public WordDistance(String[] words) {
for(int i=0;i<words.length;i++){
if(!map.containsKey(words[i])){
List<Integer> list = new ArrayList<Integer>();
map.put(words[i],list);
}
map.get(words[i]).add(i);
}
}
public int shortest(String word1, String word2) {
int min = Integer.MAX_VALUE;
List<Integer> list1 = map.get(word1);
List<Integer> list2 = map.get(word2);
for(int l1:list1){
for(int l2:list2){
min = Math.min(min,Math.abs(l1-l2));
}
}
return min;
}
}
/**
* Your WordDistance object will be instantiated and called as such:
* WordDistance obj = new WordDistance(words);
* int param_1 = obj.shortest(word1,word2);
*/