Leetcode: Shortest Word Distance II

Shortest Word Distance II

Similar Problems:

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.

You may assume that word1 does not equal to word2, and word1 and word2 are both in the list.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

  • Solution: hashmap
// Blog link: https://code.dennyzhang.com/shortest-word-distance-ii
// Basic Ideas: hashmap
//   The problem is literally about: Find the mininum difference of two lists
// Complexity: Time O(n), Space O(n)
type WordDistance struct {
    index_map map[string][]int

func Constructor(words []string) WordDistance {
    m := map[string][]int{}
    for i, word := range words {
        m[word] = append(m[word], i)
    return WordDistance{m}

func (this *WordDistance) Shortest(word1 string, word2 string) int {
    list1, list2 := this.index_map[word1], this.index_map[word2]
    res := 1<<31 - 1
    i, j := 0, 0
    for i<len(list1) && j<len(list2) {
        diff := list1[i]-list2[j]
        if diff<0 { diff = -diff }
        if diff<res { res = diff }
        if list1[i]>list2[j] { 
        } else { 
    return res

 * Your WordDistance object will be instantiated and called as such:
 * obj := Constructor(words);
 * param_1 := obj.Shortest(word1,word2);

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