check if string ' s ▁ length ▁ is ▁ less ▁ ▁ than ▁ pattern ' s length . If yes then no such window can exist
if ( $ len1 < $ len2 ) { echo " No ▁ such ▁ window ▁ exists " ; return " " ; } $ hash_pat = array_fill ( 0 , no_of_chars , 0 ) ; $ hash_str = array_fill ( 0 , no_of_chars , 0 ) ;