An algorithm for generating and arranging php cash-php Tutorial

A php algorithm for generating and ranking & lt ;? Phpfunctionperm ($ s, $ n, $ index) {if ($ n0) {return;} else {$ nIndexcount ($ index ); available string subscript $ res: a php-based algorithm for generating and arranging strings

 $ V) {$ tmp = $ index; unset ($ tmp [$ I]); // remove the current prefix/* debugging information for ease of understanding echo "len $ n, cur $ I, index: \ n "; var_dump ($ tmp); */$ ret = perm ($ s, $ n-1, $ tmp ); // recursively get a shorter arrangement if ($ ret! = '') {Foreach ($ ret as $ r) {$ res [] = $ s [$ v]. $ r; // concatenate the current prefix one by one in the shorter order} else {$ res [] = $ s [$ v] ;}} return $ res ;}} function getPerm ($ s) {$ n = strlen ($ s); $ index = range (0, $ n-1 ); // Get the for ($ I = 1; $ I <= $ n; $ I ++) {var_dump (perm ($ s, $ I, $ index) ;}} getPerm ('ABC');?>