Stumbled across this algo problem on one of Fog Creek Software's now-defunct job postings. Thought I'd try it out for practice. Fairly simple problem.

FogCreek Algo CharSort.js

// PROBLEM:
//
// Sort the characters in the following string:
// 
// abcdefghijklmnopqrstuvwxyz_
// 
// by the number of times the character appears in the following text (descending):
// 
// Note: the text scrolls.
// 
// uwlcnfcejefjudkmylhmmpjfkmhveozojepfvgboboxknkfdoghkvzxrkamhaghahpnnzh_figzhel
// kapd_dnxsiurbjgq_bcctqgigfksdrzgtxvihiqvfvinuqfzgohvilwyxpuqjolleuecpxcbisaptn
// oxbglpkhsvvwdgaminprfrha_uemwdepnngtxgkqx_flerkbnnzazcvnh_sealovrpuafumrmaizid
// jedvovhtbadjelfrbknpioqiindxqiozzpdrv_bwooblumjc_oqtcgrfmxkwkczhhqiwuqzoznqgfm
// bdxrxigvkebypbsybanuccpsezgv_dvteybbrbrbldbpiyhgzkptloxfktrzkjmdhppucsaohfnehd
// nlnhexwj_yhulslwpdreogjsffy_fkqcdkobywhqxpjvv_sqbscknxrew_ivgvpolmqfkyxoxzuyqc
// triyxcncwvvqhdupkagguee_zfbcrexbtkcsbnjcfzqoq_wrdktpsclzrmeybxpzrylfdydknd_zbj
// jqcnubpjbfaaecuxbeprjjjfcybvcghfbcvnjicpliwzkqvwo_hloynyjrmiqvubsyobetklnsgove
// sswqatrcrirsywdvbpwnhtjaug_nglxamsybkop_gnkdvgzp_cmyxclrtjtoohniuszzbnakknd_ah
// e_enbouxvpueotcjebex_vpqbwyjgczobcirmgfvwnlrxaryoltdlozwdgcp__iwu_vkod_kzkmekl
// loeixrxymlvyvtlfyydwtzxugrhxwqgmmsvtshrublypevlpglldlumsbscjuv_cbtfjpenrervyxt
// brxaaqsqs__boiiubqmgwtvzxlnxxyskbwquztepk_uggukayehrifcrdpcnrfhmlucqzbsvoojsfe
// xvbzsrccyqjuufbiae_siovpbhhqzkcemm_wtzio_d_emtkxpkpqftqjrhiiuvyijtwrmj_r_nlsaq
// emp_yph_murlmwwibzxnerld_fracudoxwqsmjkdvbfbnmkvktrkyyoct_woymzxswtd_dvs_joviu
// gjjvswlltkforlv_xdokzbqkzrojvevuuzkpcvvaarca_oeryyuasilqpwrzkyrsbskjnywidkcefj
// dekawqutrihusqtq_bjaaysidwvpmhozxcsacpehceplbihgnuaucvatj_prb_fflzfyyrndrxq__p
// txkcbhhslnuuwljwxbxzbujntztebr_knnffhl_cvxowdtpxldvsonhnfxxnmwopu_tgosofhhjhmx
// kdnvorwlsxy_cleasbnonadrgxf_bzipudfonthlclvnhumrbjkdryoawoz__ttftltixhdhd_qote
// qmyehlulpffaqmughpxxsyeevncin_ymjsnndirfg_jjcltmgphlpudrjviaixlxnpwvr_bqygvuho
// skhtv_pqnyzmjymrpnphebxqfpkfhzirotxayvclcr_zcrtsakfusyyujzdjgizngmonogwknjcndl
// pvktgntgajmzwcnkhggmhzijyrpbkpdcribyteyqchlldzeelebqjplphcdgpaaatdelz_khxpxqcl
// exvlcjiyssgsgmsddclgmsae_eubvmscpjwascwegqdxvvh_zuteauydayapfamxilyugubce_kibq
// uetsvlmguecrm_uojvkjammyevgxwfcfq_fjnauajadhsjvtsduzpmqecxfuqaaq__qhtvl_uurqaq
// uuygypqxnhrnhhiwrufntlunfqwaydimaahiihvcaycinidodqzmrnxnnxdsquwc_u_zrrkscjv_jw
// sp_xfkupx_rcbzovpsbwyiumeaanyiaqromomqldfprejqnytjftdcklykzsdupl_makofxndacjbb
// ftywdxmvmfv_wogpggfeivpfiqqlzcweelzclxkgqlvysuignftxqooofgvnopvtjy_udsf_wx_wlo
// yznfixdeyxbvqljuncfmtvjhrrrpcxowggllwcmzlp_bgwpepdntxzjbqprgdtpdbtofhwknqdarbq
// vryfaiq_lneqwlwpjpfxbmttidphupuhwghgafybhtulwkgpoavwbtixuvqroknoas_pvufqfanwdv
// zraqpxudodpifa_s_xiaef_abeawgaamorlogpmmavrwbt_bzthsnzaxzitbyuohtqswnqekujroje
// rffenhkna_nyioesdgaeofpuoyoybuweuswzaraanyzkaxuncumlsnzoavkmjoejygohgtrqtdouiu
// bigjhrutk
//                 
// Now take the sorted string, and drop all the characters
// after (and including) the _. The remaining word is the answer.

/*
  A simple problem. Counted each char in the string using 
  `string.split(char).length - 1`, then sorted into descending order,
  slicing everything off after the `_`, then displaying the result.
*/

var string = "uwlcnfcejefjudkmylhmmpjfkmhveozojepfvgboboxknkfdoghkvzxrkamhaghahpnnzh_figzhelkapd_dnxsiurbjgq_bcctqgigfksdrzgtxvihiqvfvinuqfzgohvilwyxpuqjolleuecpxcbisaptnoxbglpkhsvvwdgaminprfrha_uemwdepnngtxgkqx_flerkbnnzazcvnh_sealovrpuafumrmaizidjedvovhtbadjelfrbknpioqiindxqiozzpdrv_bwooblumjc_oqtcgrfmxkwkczhhqiwuqzoznqgfmbdxrxigvkebypbsybanuccpsezgv_dvteybbrbrbldbpiyhgzkptloxfktrzkjmdhppucsaohfnehdnlnhexwj_yhulslwpdreogjsffy_fkqcdkobywhqxpjvv_sqbscknxrew_ivgvpolmqfkyxoxzuyqctriyxcncwvvqhdupkagguee_zfbcrexbtkcsbnjcfzqoq_wrdktpsclzrmeybxpzrylfdydknd_zbjjqcnubpjbfaaecuxbeprjjjfcybvcghfbcvnjicpliwzkqvwo_hloynyjrmiqvubsyobetklnsgovesswqatrcrirsywdvbpwnhtjaug_nglxamsybkop_gnkdvgzp_cmyxclrtjtoohniuszzbnakknd_ahe_enbouxvpueotcjebex_vpqbwyjgczobcirmgfvwnlrxaryoltdlozwdgcp__iwu_vkod_kzkmeklloeixrxymlvyvtlfyydwtzxugrhxwqgmmsvtshrublypevlpglldlumsbscjuv_cbtfjpenrervyxtbrxaaqsqs__boiiubqmgwtvzxlnxxyskbwquztepk_uggukayehrifcrdpcnrfhmlucqzbsvoojsfexvbzsrccyqjuufbiae_siovpbhhqzkcemm_wtzio_d_emtkxpkpqftqjrhiiuvyijtwrmj_r_nlsaqemp_yph_murlmwwibzxnerld_fracudoxwqsmjkdvbfbnmkvktrkyyoct_woymzxswtd_dvs_joviugjjvswlltkforlv_xdokzbqkzrojvevuuzkpcvvaarca_oeryyuasilqpwrzkyrsbskjnywidkcefjdekawqutrihusqtq_bjaaysidwvpmhozxcsacpehceplbihgnuaucvatj_prb_fflzfyyrndrxq__ptxkcbhhslnuuwljwxbxzbujntztebr_knnffhl_cvxowdtpxldvsonhnfxxnmwopu_tgosofhhjhmxkdnvorwlsxy_cleasbnonadrgxf_bzipudfonthlclvnhumrbjkdryoawoz__ttftltixhdhd_qoteqmyehlulpffaqmughpxxsyeevncin_ymjsnndirfg_jjcltmgphlpudrjviaixlxnpwvr_bqygvuhoskhtv_pqnyzmjymrpnphebxqfpkfhzirotxayvclcr_zcrtsakfusyyujzdjgizngmonogwknjcndlpvktgntgajmzwcnkhggmhzijyrpbkpdcribyteyqchlldzeelebqjplphcdgpaaatdelz_khxpxqclexvlcjiyssgsgmsddclgmsae_eubvmscpjwascwegqdxvvh_zuteauydayapfamxilyugubce_kibquetsvlmguecrm_uojvkjammyevgxwfcfq_fjnauajadhsjvtsduzpmqecxfuqaaq__qhtvl_uurqaquuygypqxnhrnhhiwrufntlunfqwaydimaahiihvcaycinidodqzmrnxnnxdsquwc_u_zrrkscjv_jwsp_xfkupx_rcbzovpsbwyiumeaanyiaqromomqldfprejqnytjftdcklykzsdupl_makofxndacjbbftywdxmvmfv_wogpggfeivpfiqqlzcweelzclxkgqlvysuignftxqooofgvnopvtjy_udsf_wx_wloyznfixdeyxbvqljuncfmtvjhrrrpcxowggllwcmzlp_bgwpepdntxzjbqprgdtpdbtofhwknqdarbqvryfaiq_lneqwlwpjpfxbmttidphupuhwghgafybhtulwkgpoavwbtixuvqroknoas_pvufqfanwdvzraqpxudodpifa_s_xiaef_abeawgaamorlogpmmavrwbt_bzthsnzaxzitbyuohtqswnqekujrojerffenhkna_nyioesdgaeofpuoyoybuweuswzaraanyzkaxuncumlsnzoavkmjoejygohgtrqtdouiubigjhrutk";
var chars = Array.from("abcdefghijklmnopqrstuvwxyz_");
var counter = [];

function letterCount() {
  for(var i = 0; i < chars.length; i++) {
    counter.push(
      { 
        letter: chars[i],
        count : string.split(chars[i]).length - 1
      }
    );
  }
}

function solveWord() {
  letterCount();
  counter.sort(function (a, b) { return b.count - a.count });
  counter = counter.slice(0, counter.indexOf(counter.find(function(item){ return item.letter === "_" }))).map(function(current) { return current.letter }).join("");
  console.log(counter);
  return counter;
}

solveWord();