varalu 0 Report post Posted December 11, 2007 Write an algorithm to print all the permutations of a string. Input: man Output: man mna amn anm nam nma Give solutions optimized for Speed. Optimize for Size too. What is a permutation? Permutation is the rearrangement of objects or symbols into distinguishable sequences. Each unique ordering is called a permutation. For example, with the numerals one to six, each possible ordering consists of a complete list of the numerals, without repetitions. There are 720 total permutations of these numerals, one of which is: "4, 5, 6, 1, 2, 3". The general concept of permutation can be defined more formally in different contexts: * In set theory, a permutation is an ordered sequence containing each symbol from a set once, and only once. A permutation is distinct from a set or combination, in that the ordering of elements in a set is not considered relevant for sets or combinations. In other words, the set-theoretic definition of permutation is that of a one-to-one correspondence, or bijection, of labeled elements with "positions" or "places" which are arranged in a straight line. * In abstract algebra and related areas, the elements of permutation may not be arranged in a linear order, or indeed in any order at all. Under this refined definition, a permutation is a bijection from a finite set, X, onto itself. This allows for the definition of groups of permutations; see permutation group. * In combinatorics, the term permutation also has a traditional meaning which includes ordered lists without repetition and where one or more elements from the list are omitted from the distinguishable orderings; for example, a permutation of "1,2,4,3" with "5" and "6" omitted. Here i have one possible solution from my friend.... (Pallavi) 1.Concat the input string with itself : manman 2. initialise the ptr to first element 3. Print it length of the string 4. Move the ptr by one position ( keep incrementing till length times) and perform step 3 5. reverse the whole string and repeat steps 2, 3, 4 Any better solutions? WELCOME !!! Share this post Link to post Share on other sites

laexter 0 Report post Posted December 12, 2007 $tmp = array();$s = 'the string you wish to permute, in the example, e.g. man';$out = '';$ctr=0;function perm($ctr) { global $out; global $s; global $tmp; //echo $out; if ($ctr == strlen($s)) { echo $out . "\n"; } else { for ($i=0;$i<strlen($s);$i++) { //echo 'a'; if (!$tmp[$i]) { $tmp[$i]=TRUE; $out .= $s[$i]; perm($ctr+1); $tmp[$i]=FALSE; $out = substr($out, 0, -1); } } }}perm(0); is something I have in my computer. (it is PHP if you haven't noticed) Share this post Link to post Share on other sites

iGuest 3 Report post Posted December 17, 2009 permutation of a string.....solutionData Structure -- Permutations#include<iostream>#include<cstring>Using namespace std;Void permutation(char *str,char *suffix=""){ if(strlen(str)==0) {printf("%sand",suffix); return;} int I,j,count,l=strlen(str); char *smaller[l]; for(I=0;I<l;I++) smaller=(char*)malloc(l*sizeof(char)); //--------------------- int s=strlen(suffix); char *suffix_temp =(char*) malloc((s+2)*sizeof(char)); for(I=0;suffix!='0';I++) suffix_temp=suffix; //--------------------- for(I=0;I<l;I++) { count=0; for(j=(I+1)%l;j!=I;j=(j+1)%l) smaller[count++]=str[j]; smaller[count]='0'; suffix_temp=str; suffix_temp[s+1]='0'; permutation(smaller,suffix_temp); }}int main(){ char *str="ABCD"; permutation(str); system("pause"); return 0;}//--------------------------------------------------------- Share this post Link to post Share on other sites