Implement a routine that prints all the permutations of a given string.
Do not use recursion.
function permute(str) { /*from w ww.j av a 2 s. c o m*/ } /* 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 */
/** * @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 */