245. Shortest Word Distance III

// LeetCode URL: https://leetcode.com/problems/shortest-word-distance-iii/

/**
 * Refer :
 * https://leetcode.com/problems/shortest-word-distance-iii/discuss/67097/12-16-lines-Java-C++
 *
 * Time Complexity: O(L * N)
 *
 * Space Complexity: O(1)
 *
 * L = Average length of a word in words array. N = Number words in the input
 * array.
 */
class Solution {
    public int shortestWordDistance(String[] words, String word1, String word2) {
        if (words == null || words.length == 0 || word1 == null || word2 == null) {
            return -1;
        }

        boolean same = word1.equals(word2);
        int result = Integer.MAX_VALUE;
        int index1 = -1;
        int index2 = -1;

        for (int i = 0; i < words.length; i++) {
            if (words[i].equals(word1)) {
                index1 = i;
            }
            if (words[i].equals(word2)) {
                if (same) {
                    // In case of word1 == word2, index1 will store the previous occurance of the
                    // word.
                    index1 = index2;
                }
                index2 = i;
            }
            if (index1 != -1 && index2 != -1) {
                result = Math.min(result, Math.abs(index1 - index2));
            }
        }

        return result == Integer.MAX_VALUE ? -1 : result;
    }
}