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# 0245. Shortest Word Distance III

<https://leetcode.com/problems/shortest-word-distance-iii>

## Description

Given an array of strings `wordsDict` and two strings that already exist in the array `word1` and `word2`, return *the shortest distance between these two words in the list*.

**Note** that `word1` and `word2` may be the same. It is guaranteed that they represent **two individual words** in the list.

**Example 1:**

```
**Input:** wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "coding"
**Output:** 1
```

**Example 2:**

```
**Input:** wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "makes"
**Output:** 3
```

**Constraints:**

* `1 <= wordsDict.length <= 105`
* `1 <= wordsDict[i].length <= 10`
* `wordsDict[i]` consists of lowercase English letters.
* `word1` and `word2` are in `wordsDict`.

## ac2

this one is stupid, why you need to have a map? a waste time and space.

```java
class Solution {
    public int shortestWordDistance(String[] words, String word1, String word2) {
        // edge cases
        if (words.length < 2) return 0;

        Map<String, List<Integer>> map = new HashMap<String, List<Integer>>();

        // walk array, get map
        for (int i = 0; i < words.length; i++) {
            if (map.containsKey(words[i])) {
                map.get(words[i]).add(i);
            } else {
                List<Integer> tmp = new ArrayList<Integer>();
                tmp.add(i);
                map.put(words[i], tmp);
            }
        }

        return minDiff(map.get(word1), map.get(word2));
    }

    private int minDiff(List<Integer> l1, List<Integer> l2) {
        int diff = Integer.MAX_VALUE;

        // same list, same word
        if (l1 == l2) {
            for (int i = 1; i < l1.size(); i++) {
                diff = Math.min(diff,
                               Math.abs(l1.get(i) - l1.get(i-1)));
            }
            return diff;
        }

        // binary search longer one
        List<Integer> s = l1, l = l2;
        if (l1.size() > l2.size()) {
            l = l1; s = l2;
        }
        for (int i = 0; i < s.size(); i++) {
            int target = s.get(i);
            int left = 0, right = l.size()-1;
            while (left + 1 < right) {
                int mid = left + (right - left) / 2;
                if (l.get(mid) > target) right = mid;
                else left = mid;
            }
            diff = Math.min(diff, 
                                 Math.min(Math.abs(l.get(left) - target), Math.abs(l.get(right) - target)));
        }

        return diff;
    }
}
```

## ac2

```java
class Solution {
    public int shortestWordDistance(String[] words, String word1, String word2) {
        // edge cases
        if (words.length < 2) return 0;

        int prev = -1;
        int diff = Integer.MAX_VALUE;
        for (int i = 0; i < words.length; i++) {
            if (words[i].equals(word1) || words[i].equals(word2)) {
                if (prev != -1) {
                    if (word1.equals(word2)) {
                        diff = Math.min(diff, i - prev);
                    } else if(!words[i].equals(words[prev])) {
                        diff = Math.min(diff, i - prev);
                    }
                }
                prev = i;
            }
        }

        return diff;
    }
}
```

## ac3

```java
// intuition: 1) time complexity can be optimized? 2) space can be optimized?
class Solution {
    public int shortestWordDistance(String[] words, String word1, String word2) {
        // edge cases
        if (words.length < 2) return 0;

        int i1 = -1, i2 = -1;
        int diff = Integer.MAX_VALUE;
        for (int i = 0; i < words.length; i++) {
            if (words[i].equals(word1)) {
                if (word1.equals(word2)) {
                    i2 = i1;
                    i1 = i;
                } else {
                    i1 = i;
                }
            } else if (words[i].equals(word2)) {
                i2 = i;
            }

            if (i1 >= 0 && i2 >= 0) diff = Math.min(diff,
                                                   Math.abs(i1-i2));
        }

        return diff;
    }
}
```