CodeWars/6kyu/consecutive_strings/solution.java

class LongestConsec {
    public static String longestConsec(String[] strarr, int k) {
        int n = strarr.length;

        // handle limits
        if (n == 0 || k <= 0 || k > n) {
            return "";
        }

        // determine lengths
        int[] lengths = new int[n];
        for (int i = 0; i < n; i++) {
          lengths[i] = strarr[i].length();
        }

        // calculate first index
        int maxIndex = 0, maxLength = 0;
        for (int i = 0; i < k; i++) {
            maxLength += lengths[i];
        }

        // Check rest of the array
        int tmpLength = maxLength;
        for (int i = 1; i < n - k + 1; i++) {
            tmpLength += lengths[i + k - 1];
            tmpLength -= lengths[i - 1];

            if (tmpLength > maxLength) {
                maxIndex = i;
                maxLength = tmpLength;
            }
        }

        // Join the strings
        String result = "";
        for (int i = maxIndex; i < maxIndex + k; i++) {
            result += strarr[i];
        }

        return result;
    }
}