iframe-proxy | Sunbelt Computer Software

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* <!--

* This program is distributed under

* the terms of the MIT license.

* Please see the LICENSE file for details.

* -->

* Implement a routine that prints all the permutations of a given string.

* Do *not* use recursion.

/*____________________________________________________________________________*/

/**

* @function {public static} swap

* Swaps the two characters of a given string.

* @param {String} str - the `String` to swap.

* @param {Integer} i - the first character index.

* @param {Integer} j - the second character index.

* @return the swapped `String`.

function swap(str, i, j) {

var ar = str.split('');

var temp = ar[i];

ar[i] = ar[j];

ar[j] = temp;

return ar.join('');

}

/**

* A helper.

function print(str) {

console.log(str);

}

/**

* @function {public static} permute

* Iteratively permutes the `String` using

* the "CountDown QuickPerm Algorithm".

* ref: http://permute.tchs.info/01example.php

* @param {String} str - the `String` to permute.

function permute(str) {

var len = str.length;

var p = [];

for(var i=0; i<len+1; i++) {

p[i] = i;

}

var i = 1;

var j = 0;

print(str);

while (i < len) {

p[i] -= 1;

j = (i%2 === 0) ? 0 : p[i];

str = swap(str, j, i);

print(str);

i = 1;

while (p[i] === 0) {

p[i] = i;

i++;

}

/*____________________________________________________________________________*/

permute('SF_CA');

Output: ($ /usr/bin/node 007.js)

SF_CA

FS_CA

_SFCA

S_FCA

F_SCA

_FSCA

_FCSA

F_CSA

C_FSA

_CFSA

FC_SA

CF_SA

CS_FA

SC_FA

_CSFA

C_SFA

S_CFA

_SCFA

FSC_A

SFC_A

CFS_A

FCS_A

SCF_A

CSF_A

ASF_C

SAF_C

FAS_C

AFS_C

SFA_C

FSA_C

FS_AC

SF_AC

_FSAC

F_SAC

S_FAC

_SFAC

_AFSC

A_FSC

F_ASC

_FASC

AF_SC

FA_SC

SA_FC

AS_FC

_SAFC

S_AFC

A_SFC

_ASFC

CASF_

ACSF_

SCAF_

CSAF_

ASCF_

SACF_

SAFC_

ASFC_

FSAC_

SFAC_

AFSC_

FASC_

FCSA_

CFSA_

SFCA_

FSCA_

CSFA_

SCFA_

ACFS_

CAFS_

FACS_

AFCS_

CFAS_

FCAS_

_CASF

C_ASF

A_CSF

_ACSF

CA_SF

AC_SF

ACS_F

CAS_F

SAC_F

ASC_F

CSA_F

SCA_F

S_ACF

_SACF

AS_CF

SA_CF

_ASCF

A_SCF

C_SAF

_CSAF

SC_AF

CS_AF

_SCAF

S_CAF

F_CAS

_FCAS

CF_AS

FC_AS

_CFAS

C_FAS

C_AFS

_CAFS

AC_FS

CA_FS

_ACFS

A_CFS

AFC_S

FAC_S

CAF_S

ACF_S

FCA_S

CFA_S

_FACS

F_ACS

A_FCS

_AFCS

FA_CS

AF_CS

Sunbelt Computer Software

PL/B Language Development and Support

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Sunbelt Computer Software

PL/B Language Development and Support

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