AOC 2022 Day 6 parts 1+2 (AWK)

{
    MARKER_SIZE = 4; # 14 for part 2;
    while (n+=1) {
            if (isCharsUnique(substr($0, n, MARKER_SIZE))) {
                    print n + MARKER_SIZE - 1; break;
            }
    }
}

func isCharsUnique(string,   i, ar) {
    for (i=1;i<=length(string);i++) {
            ar[substr(string, i, 1)] = 1;
    }
    return length(ar) == length(string);
}