aoc2022/d06/exec.awk

BEGIN { W = 14 }
{
	for (i=1; i<=length($1); i++) {
		window = substr($1,i,W)
		# compare each char of the window to rest of the window
		S = 0  # to count match
		for (j=1; j<=W; j++) {
			for (k=j+1; k<=W; k++) {
				S+= (substr(window,j,1) == substr(window,k,1)) ? 1 : 0
			}
		}
		if (S == 0) {
			print i + W - 1
			next
		}
	}
}