Leetcode 243. Shortest Word Distance

[locked]
Given a list of words and two words word1 and word2, 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.

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This definition of distance is a little bit strange indeed. However this problem is not very hard and we have many ways to solve it. For example, hash table. Or we can save space by using two indexes to record and calculate distance every time and get the min distance.

# Time:  O(n)
# Space: O(1)

class Solution:
    # @param {string[]} words
    # @param {string} word1
    # @param {string} word2
    # @return {integer}
    def shortestDistance(self, words, word1, word2):
        dist = float("inf")
        i, index1, index2 = 0, None, None
        while i < len(words):
            if words[i] == word1:
                index1 = i
            elif words[i] == word2:
                index2 = i

            if index1 is not None and index2 is not None:
                dist = min(dist, abs(index1 - index2))
            i += 1

        return dist