Leetcode - Shortest Word Distance II

https://leetcode.com/problems/shortest-word-distance-ii/

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. Your method will be called repeatedly many times with different parameters. 

Example:
Assume that words = ["practice", "makes", "perfect", "coding", "makes"].

Input: word1 = “coding”, word2 = “practice”
Output: 3

Input: word1 = "makes", word2 = "coding"
Output: 1

1. Use a hash to track every word index

2. Find min distance for two arrays. Since the arrays have been sorted, it can use the idea of merge sort to find the minimum distance.

type WordDistance struct {
    wordHash map[string][]int
}


func Constructor(words []string) WordDistance {
    wordHash := map[string][]int{}
    for i, w := range words {
        _, ok := wordHash[w]
        if ok {
            wordHash[w] = append(wordHash[w], i)
        } else {
            wordHash[w] = []int{i}
        }
    }
    return WordDistance{
        wordHash: wordHash,
    }
}


func (this *WordDistance) Shortest(word1 string, word2 string) int {
    arr1 := this.wordHash[word1]
    arr2 := this.wordHash[word2]
    min := math.MaxInt32
    w1Index := 0
    w2Index := 0
    for w1Index < len(arr1) && w2Index < len(arr2) {
        tmp := abs(arr1[w1Index] - arr2[w2Index])
        if tmp < min {
            min = tmp
        }
        if arr1[w1Index] < arr2[w2Index] {
            w1Index++
        } else {
            w2Index++
        }
    }
    return min
}


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

func abs(a int) int {
    if a < 0 {
        return 0 - a
    }
    return a
}

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