day7

This one was a little trickier, as the obvious solution for navigating back up a tree is to keep a reference to the parent.
However that's essentially a doubly linked list which is a pain in the ass in Rust.
Instead, use a separate variable for the current 'key' into the tree

I'm not especially happy with the terminal processing as well, since after the 'ls' command we need to 'peek' at the next entry to see if the 'ls' has finished and we're onto a next command
I couldn't think of a very good way to do this except loops and loops.

4 files changed, 1188 insertions, 0 deletions

diff --git a/input/day7.txt b/input/day7.txt
new file mode 100644
index 0000000..34cee8d
--- /dev/null
+++ b/input/day7.txt
@@ -0,0 +1,1031 @@
+$ cd /
+$ ls
+150555 bch.lht
+276291 ccqfdznj.sqg
+dir csmqbhjv
+dir czdqfr
+dir fpfwfzrt
+192660 qnbzgp
+142026 rpphgdhp.jfr
+dir sqphfslv
+38077 tvpzh
+$ cd csmqbhjv
+$ ls
+52822 bch.lht
+dir dgj
+dir fmmblb
+dir hjwwtw
+dir mtmhst
+dir njsccfms
+dir wmjsvq
+$ cd dgj
+$ ls
+266484 bch.lht
+dir brwncbh
+dir dtdzsqps
+216678 gvmdvcs.fmq
+225948 mdjrhmhf
+dir tvpzh
+301487 tvpzh.wbp
+2555 whsnd.spb
+$ cd brwncbh
+$ ls
+238441 jwmr.plh
+$ cd ..
+$ cd dtdzsqps
+$ ls
+294443 fmmblb
+81441 nsljm.fcz
+$ cd ..
+$ cd tvpzh
+$ ls
+186671 bch.lht
+dir czdqfr
+dir fgmz
+300898 gvmdvcs.fmq
+dir rjnv
+dir szcrlzmr
+dir tvpzh
+dir vbrn
+$ cd czdqfr
+$ ls
+dir czdqfr
+dir hrhqhcjg
+$ cd czdqfr
+$ ls
+8551 zmcqmq.zvf
+$ cd ..
+$ cd hrhqhcjg
+$ ls
+8255 wfvj.lnd
+$ cd ..
+$ cd ..
+$ cd fgmz
+$ ls
+145921 wfvj.lnd
+$ cd ..
+$ cd rjnv
+$ ls
+305697 bch.lht
+dir cdqv
+dir czdqfr
+288685 nsjnqh.fzq
+210447 qlg
+34660 rbnlc.gmc
+143353 vsjg.njm
+$ cd cdqv
+$ ls
+294789 czdqfr.nvt
+$ cd ..
+$ cd czdqfr
+$ ls
+298572 bch.lht
+dir fmmblb
+5599 tvpzh.pnf
+47873 vmm
+$ cd fmmblb
+$ ls
+dir cjtb
+dir llg
+dir rcb
+190831 rwf.rzd
+$ cd cjtb
+$ ls
+306568 fmmblb.hns
+$ cd ..
+$ cd llg
+$ ls
+68274 hbj.glq
+261526 jplstj
+285699 rmq
+$ cd ..
+$ cd rcb
+$ ls
+dir lmgrr
+$ cd lmgrr
+$ ls
+306217 bch.lht
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd szcrlzmr
+$ ls
+dir mdjrhmhf
+195828 pnllrfpr.lhl
+dir rns
+286738 sgzhcwj
+$ cd mdjrhmhf
+$ ls
+dir clmdlmc
+dir fmmblb
+299416 fmmblb.ftr
+dir mnm
+22720 zpgvqpbr.glm
+$ cd clmdlmc
+$ ls
+289014 fmmblb.njt
+246797 gvmdvcs.fmq
+92044 tvpzh.cfj
+$ cd ..
+$ cd fmmblb
+$ ls
+81512 czdqfr.ltc
+173394 ntcdzdc.spn
+$ cd ..
+$ cd mnm
+$ ls
+260096 bch.lht
+dir czdqfr
+dir rwnqgjmm
+$ cd czdqfr
+$ ls
+269467 nfphbtz
+$ cd ..
+$ cd rwnqgjmm
+$ ls
+218872 ldflbsm.rzh
+256978 lwhhc
+dir pgrtzw
+$ cd pgrtzw
+$ ls
+32086 gvmdvcs.fmq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd rns
+$ ls
+282353 fcwhvqd.qvb
+dir fwjb
+dir prdd
+dir rtrglmt
+$ cd fwjb
+$ ls
+dir jlhqd
+217527 tgvqql
+$ cd jlhqd
+$ ls
+196505 qbrbcrgt.wqj
+$ cd ..
+$ cd ..
+$ cd prdd
+$ ls
+144295 brwncbh
+87560 dsrm
+$ cd ..
+$ cd rtrglmt
+$ ls
+219787 tcsrq.wzt
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd tvpzh
+$ ls
+dir swrgwp
+$ cd swrgwp
+$ ls
+dir cqzs
+dir wtcsc
+$ cd cqzs
+$ ls
+284674 rlhjp.dlf
+$ cd ..
+$ cd wtcsc
+$ ls
+50313 wfvj.lnd
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd vbrn
+$ ls
+11650 czdqfr.ccz
+dir fmmblb
+145626 whsnd.spb
+$ cd fmmblb
+$ ls
+204558 rdh.rms
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fmmblb
+$ ls
+dir bhvpslz
+$ cd bhvpslz
+$ ls
+dir jsmrb
+$ cd jsmrb
+$ ls
+1472 fgctpsl.rgf
+258119 whsnd.spb
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd hjwwtw
+$ ls
+291890 fmmblb.zrt
+$ cd ..
+$ cd mtmhst
+$ ls
+dir dfqm
+dir fmmblb
+178539 jtmflfb
+dir mdjrhmhf
+dir rdzg
+dir tvpzh
+dir wqlf
+$ cd dfqm
+$ ls
+dir czdqfr
+dir fmmblb
+dir gngvhs
+dir ppjdlbp
+dir shs
+dir srdrb
+$ cd czdqfr
+$ ls
+85242 gwqzn.ppr
+$ cd ..
+$ cd fmmblb
+$ ls
+76800 bqbnwdq.zfr
+72865 fmmblb
+119311 hfbtwgb.nmn
+305342 wfvj.lnd
+$ cd ..
+$ cd gngvhs
+$ ls
+dir fmmblb
+dir jfptn
+dir jlqzq
+dir mdjrhmhf
+dir scmjf
+dir tvpzh
+$ cd fmmblb
+$ ls
+174392 whsnd.spb
+$ cd ..
+$ cd jfptn
+$ ls
+dir vjm
+$ cd vjm
+$ ls
+193871 bch.lht
+$ cd ..
+$ cd ..
+$ cd jlqzq
+$ ls
+dir fmmblb
+187410 hcfdppj.hjh
+dir mdjrhmhf
+dir nhb
+107865 qntnnqcp
+dir wlqjpsh
+$ cd fmmblb
+$ ls
+dir ccpvdzg
+240944 fqsjc.cmc
+$ cd ccpvdzg
+$ ls
+304195 whsnd.spb
+$ cd ..
+$ cd ..
+$ cd mdjrhmhf
+$ ls
+242269 whsnd.spb
+$ cd ..
+$ cd nhb
+$ ls
+83616 mtfq
+$ cd ..
+$ cd wlqjpsh
+$ ls
+249472 gdg
+$ cd ..
+$ cd ..
+$ cd mdjrhmhf
+$ ls
+213465 bbsltzd.fvd
+dir tqmwn
+$ cd tqmwn
+$ ls
+54460 bwnztql
+262257 gvmdvcs.fmq
+$ cd ..
+$ cd ..
+$ cd scmjf
+$ ls
+dir fhfg
+268890 wqdcbprh
+$ cd fhfg
+$ ls
+234806 whsnd.spb
+$ cd ..
+$ cd ..
+$ cd tvpzh
+$ ls
+79625 zqbsb.mnq
+$ cd ..
+$ cd ..
+$ cd ppjdlbp
+$ ls
+249976 zdqlmnll.nps
+$ cd ..
+$ cd shs
+$ ls
+107840 bsfcgmrw.dzw
+dir fmmblb
+307016 gvmdvcs.fmq
+185876 jjhdj.vpn
+254920 ltmp
+dir rrg
+312847 whsnd.spb
+$ cd fmmblb
+$ ls
+161417 wppzrz.hjz
+$ cd ..
+$ cd rrg
+$ ls
+304639 bch.lht
+$ cd ..
+$ cd ..
+$ cd srdrb
+$ ls
+dir bgchgtg
+238106 hcfdppj.hjh
+dir lgz
+dir zmlm
+$ cd bgchgtg
+$ ls
+dir hhbmwp
+166735 psbpml.jdb
+dir rtdwhlsq
+171684 zcb.dlr
+$ cd hhbmwp
+$ ls
+105599 cppw.mlb
+dir dvzmpfzn
+72811 fmmblb.bdd
+293591 fnh.fdv
+dir fspwz
+dir gznwz
+259403 tvpzh.bfj
+$ cd dvzmpfzn
+$ ls
+127885 nbb.jgs
+126415 whsnd.spb
+$ cd ..
+$ cd fspwz
+$ ls
+dir fzpfbcvv
+dir jzrqvds
+$ cd fzpfbcvv
+$ ls
+114984 czdqfr.pmn
+157782 gzwrcdp.mtz
+$ cd ..
+$ cd jzrqvds
+$ ls
+47749 hcfdppj.hjh
+$ cd ..
+$ cd ..
+$ cd gznwz
+$ ls
+77780 lnbtzj.bhz
+$ cd ..
+$ cd ..
+$ cd rtdwhlsq
+$ ls
+300900 bbs
+dir cchdchd
+246695 djbmcmn
+195895 fvwm.hrd
+67210 hcfdppj.hjh
+101017 zhnvhfm.wps
+$ cd cchdchd
+$ ls
+52763 gvmdvcs.fmq
+124993 tvpzh.nwc
+dir zzsbq
+$ cd zzsbq
+$ ls
+263814 zvhnm.sbv
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd lgz
+$ ls
+121541 wfvj.lnd
+134550 whsnd.spb
+$ cd ..
+$ cd zmlm
+$ ls
+91948 cjqdnnh.hzr
+250728 czdqfr.zjb
+dir jnbhfnn
+dir rnmghbht
+dir tjhnp
+144737 whsnd.spb
+$ cd jnbhfnn
+$ ls
+49839 whsnd.spb
+$ cd ..
+$ cd rnmghbht
+$ ls
+69330 hcjspd
+dir mfgbbvcc
+dir qdh
+$ cd mfgbbvcc
+$ ls
+dir gmgdfss
+$ cd gmgdfss
+$ ls
+266023 hcfdppj.hjh
+dir mdjrhmhf
+dir ndcmqpc
+291530 vqwf.bfc
+$ cd mdjrhmhf
+$ ls
+dir brwncbh
+$ cd brwncbh
+$ ls
+dir fmmblb
+$ cd fmmblb
+$ ls
+dir ppwp
+$ cd ppwp
+$ ls
+299841 mdjrhmhf.bdg
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ndcmqpc
+$ ls
+71727 mdjrhmhf.njs
+218233 nwvfb.qzt
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd qdh
+$ ls
+294005 jgbcmg.hjg
+$ cd ..
+$ cd ..
+$ cd tjhnp
+$ ls
+dir vhjtqdg
+$ cd vhjtqdg
+$ ls
+28638 gvmdvcs.fmq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fmmblb
+$ ls
+111152 cnvzdz.cdb
+252709 gvmdvcs.fmq
+168368 lpfbzh
+dir mdjrhmhf
+dir mzrzzhpt
+72606 qbbllr.shq
+160820 whsnd.spb
+$ cd mdjrhmhf
+$ ls
+32945 fmmblb.jpf
+$ cd ..
+$ cd mzrzzhpt
+$ ls
+dir gdsv
+130898 hcfdppj.hjh
+44339 hvnqt
+dir mdjrhmhf
+297785 mdwng.pbr
+dir wwqmlhgg
+281612 zvftqhm.pzl
+$ cd gdsv
+$ ls
+10562 cprgfn
+$ cd ..
+$ cd mdjrhmhf
+$ ls
+284882 dpjs
+202491 lrtgstpp.grn
+3714 wfvj.lnd
+$ cd ..
+$ cd wwqmlhgg
+$ ls
+84563 fwvhfrh.cfp
+4654 hcfdppj.hjh
+248672 whsnd.spb
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd mdjrhmhf
+$ ls
+dir mdjrhmhf
+25175 mdjrhmhf.nrg
+dir mslwjsp
+207567 prrqb.qwj
+282436 tvpzh.hjh
+$ cd mdjrhmhf
+$ ls
+43516 jzrjwdd.vss
+27326 wfvj.lnd
+$ cd ..
+$ cd mslwjsp
+$ ls
+141951 cqvh.zzq
+$ cd ..
+$ cd ..
+$ cd rdzg
+$ ls
+312895 brwncbh.cpb
+$ cd ..
+$ cd tvpzh
+$ ls
+228240 bch.lht
+dir fjtwlj
+dir jnpgqsb
+90201 ldh
+271575 rfhh.vzr
+69760 whsnd.spb
+$ cd fjtwlj
+$ ls
+46126 rhdr.jgg
+$ cd ..
+$ cd jnpgqsb
+$ ls
+dir rllbvnm
+$ cd rllbvnm
+$ ls
+212620 hcfdppj.hjh
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd wqlf
+$ ls
+210864 fmmblb
+dir jswfprpl
+dir nztbsbq
+$ cd jswfprpl
+$ ls
+dir fmmblb
+dir lmwz
+dir qvj
+$ cd fmmblb
+$ ls
+201940 mhjlhc.npl
+$ cd ..
+$ cd lmwz
+$ ls
+dir brwncbh
+dir dhff
+288199 flgch
+187825 gvmdvcs.fmq
+203272 nvfllgvn.cjj
+dir tvpzh
+dir vrv
+53288 zsrz.mrd
+$ cd brwncbh
+$ ls
+174732 whsnd.spb
+$ cd ..
+$ cd dhff
+$ ls
+dir lddw
+dir mfwnzprw
+222134 tvpzh.gfm
+$ cd lddw
+$ ls
+296685 bch.lht
+$ cd ..
+$ cd mfwnzprw
+$ ls
+6260 dvrcqzp.pmd
+$ cd ..
+$ cd ..
+$ cd tvpzh
+$ ls
+dir gmvswdr
+dir hfzdqdz
+dir hhjwt
+228542 htljf.tfl
+57417 mdjrhmhf
+248369 whsnd.spb
+$ cd gmvswdr
+$ ls
+215582 fnzh.mhs
+$ cd ..
+$ cd hfzdqdz
+$ ls
+82080 dcw.vmt
+142007 fmmblb.fnq
+dir ggqcqcc
+36091 hcfdppj.hjh
+219562 mqb.qsm
+2323 wfvj.lnd
+$ cd ggqcqcc
+$ ls
+4679 whsnd.spb
+$ cd ..
+$ cd ..
+$ cd hhjwt
+$ ls
+dir lbqpgd
+dir tdb
+$ cd lbqpgd
+$ ls
+177175 wfvj.lnd
+$ cd ..
+$ cd tdb
+$ ls
+270893 bch.lht
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd vrv
+$ ls
+dir bqmnhdts
+171679 czdqfr
+$ cd bqmnhdts
+$ ls
+64972 pjzzs.qqd
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd qvj
+$ ls
+dir bfwtb
+dir bpnppqg
+271362 gcs.srv
+dir gvlqddlb
+70000 gzdr.ndb
+103231 pwspfm
+dir swgfvtf
+$ cd bfwtb
+$ ls
+200600 czdqfr.sbv
+dir wmbhgcw
+$ cd wmbhgcw
+$ ls
+310044 zwfrcld.mtb
+$ cd ..
+$ cd ..
+$ cd bpnppqg
+$ ls
+120203 dggplss.whb
+$ cd ..
+$ cd gvlqddlb
+$ ls
+12163 bch.lht
+154059 llpw
+dir pglr
+dir rbfpbcpd
+dir rstg
+209132 tvpzh.djc
+287422 wlhjvsz
+$ cd pglr
+$ ls
+145907 brwncbh.cqp
+$ cd ..
+$ cd rbfpbcpd
+$ ls
+292475 brwncbh
+dir czdqfr
+dir dcnh
+dir fmmblb
+dir qwrsrdr
+$ cd czdqfr
+$ ls
+66107 tvpzh.wfd
+$ cd ..
+$ cd dcnh
+$ ls
+297110 rpzsrws.sft
+$ cd ..
+$ cd fmmblb
+$ ls
+25829 wmmhq
+$ cd ..
+$ cd qwrsrdr
+$ ls
+199762 fmmblb.qpm
+$ cd ..
+$ cd ..
+$ cd rstg
+$ ls
+236706 bch.lht
+$ cd ..
+$ cd ..
+$ cd swgfvtf
+$ ls
+227938 lrbcddd.btw
+282992 rlnwrd
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd nztbsbq
+$ ls
+116544 czdqfr
+dir fhwmhvdn
+68451 gvmdvcs.fmq
+247136 hcfdppj.hjh
+dir mzvq
+dir tvpzh
+dir wtllfshw
+$ cd fhwmhvdn
+$ ls
+122155 cmtlhcdw
+39927 twbfczfb.lcp
+$ cd ..
+$ cd mzvq
+$ ls
+dir lnjtfgh
+$ cd lnjtfgh
+$ ls
+161712 phfn
+$ cd ..
+$ cd ..
+$ cd tvpzh
+$ ls
+dir jgpr
+dir mdjrhmhf
+dir rnntmvpr
+$ cd jgpr
+$ ls
+85238 gvmdvcs.fmq
+$ cd ..
+$ cd mdjrhmhf
+$ ls
+231007 gzrsgvp
+$ cd ..
+$ cd rnntmvpr
+$ ls
+285020 tvpzh
+$ cd ..
+$ cd ..
+$ cd wtllfshw
+$ ls
+135281 gvmdvcs.fmq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd njsccfms
+$ ls
+dir zdddqvq
+$ cd zdddqvq
+$ ls
+91520 whmwbpd
+$ cd ..
+$ cd ..
+$ cd wmjsvq
+$ ls
+dir fmmblb
+dir htmb
+dir lmzhpth
+dir mrjq
+142052 wldwl
+$ cd fmmblb
+$ ls
+173331 fmmblb.fbm
+$ cd ..
+$ cd htmb
+$ ls
+dir gtm
+$ cd gtm
+$ ls
+7647 hcfdppj.hjh
+$ cd ..
+$ cd ..
+$ cd lmzhpth
+$ ls
+dir tvpzh
+dir vdqg
+dir zvhmfm
+$ cd tvpzh
+$ ls
+259073 wfvj.lnd
+$ cd ..
+$ cd vdqg
+$ ls
+199919 bch.lht
+169430 fmmblb.ttq
+231127 hcfdppj.hjh
+$ cd ..
+$ cd zvhmfm
+$ ls
+274752 gvmdvcs.fmq
+$ cd ..
+$ cd ..
+$ cd mrjq
+$ ls
+dir fqcspsv
+dir fvvmlbf
+252802 gnclv
+82538 gvmdvcs.fmq
+296461 jvbnhrpd
+104809 lbh
+46038 tfq.gtv
+$ cd fqcspsv
+$ ls
+dir fjqnf
+$ cd fjqnf
+$ ls
+dir tvpzh
+$ cd tvpzh
+$ ls
+dir lhwdrcwz
+$ cd lhwdrcwz
+$ ls
+129410 lcd.dzd
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fvvmlbf
+$ ls
+263142 brwncbh.fgg
+232863 cvwv
+100409 qphswnlb.vpq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd czdqfr
+$ ls
+dir czdqfr
+307029 lntbmr.brq
+dir mdjrhmhf
+dir tvpzh
+$ cd czdqfr
+$ ls
+289585 gvmdvcs.fmq
+$ cd ..
+$ cd mdjrhmhf
+$ ls
+137110 brwncbh.dbt
+$ cd ..
+$ cd tvpzh
+$ ls
+258325 wfvj.lnd
+$ cd ..
+$ cd ..
+$ cd fpfwfzrt
+$ ls
+221993 hcfdppj.hjh
+56206 lphphf.thd
+255850 mdjrhmhf.hqt
+$ cd ..
+$ cd sqphfslv
+$ ls
+104415 mdjrhmhf.gbr
+dir pjtzm
+dir spnr
+61982 stbwbpzf.hwm
+$ cd pjtzm
+$ ls
+dir brwncbh
+178769 jnmgzcqh.mht
+dir tvpzh
+153193 tvpzh.cdc
+dir zstcqndd
+$ cd brwncbh
+$ ls
+117400 brwncbh.mvq
+dir fbzvn
+3239 fmmblb.hzm
+73631 hqtnwbgw
+dir npzf
+172382 pdgg
+$ cd fbzvn
+$ ls
+152876 bch.lht
+293370 czc.jtt
+43408 czdqfr
+dir fqg
+105569 qqmcwjz.bzd
+19734 whsnd.spb
+$ cd fqg
+$ ls
+88780 jffmmm.qff
+22385 lqrhch.vlm
+$ cd ..
+$ cd ..
+$ cd npzf
+$ ls
+190792 pdtlbrqt.ghq
+$ cd ..
+$ cd ..
+$ cd tvpzh
+$ ls
+dir blgjrjt
+dir dlzjtlbt
+dir jnwm
+dir qprbng
+305178 tbvg
+dir tvpzh
+308117 wrbldl.jhp
+$ cd blgjrjt
+$ ls
+125644 bch.lht
+104319 ctglz.lmd
+131972 hcfdppj.hjh
+312663 tbgqwf
+$ cd ..
+$ cd dlzjtlbt
+$ ls
+98262 bvfldnd.sls
+173244 dlmf.mzh
+75842 rlbpgjh.wtb
+$ cd ..
+$ cd jnwm
+$ ls
+58963 vjftmflp.dcs
+$ cd ..
+$ cd qprbng
+$ ls
+308054 fzbrm.jdt
+310679 gnwn.psf
+257810 tpsgjjdq.mdw
+dir tvpzh
+305633 vpbwhqs.cqb
+$ cd tvpzh
+$ ls
+220904 rlpj.rdc
+$ cd ..
+$ cd ..
+$ cd tvpzh
+$ ls
+dir fmmblb
+$ cd fmmblb
+$ ls
+104020 crhq.pnb
+74914 czdqfr
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd zstcqndd
+$ ls
+dir brwncbh
+dir jwpbtpr
+306359 ljg
+dir wbssjjd
+$ cd brwncbh
+$ ls
+114145 wfvj.lnd
+$ cd ..
+$ cd jwpbtpr
+$ ls
+94567 bch.lht
+dir czdqfr
+dir fsqvbv
+134187 wnpcqmw.tws
+$ cd czdqfr
+$ ls
+dir mdjrhmhf
+$ cd mdjrhmhf
+$ ls
+122398 mdjrhmhf.zts
+dir svhh
+101920 whsnd.spb
+dir zcsnqjj
+$ cd svhh
+$ ls
+120875 tvpzh.jls
+$ cd ..
+$ cd zcsnqjj
+$ ls
+279979 tljnvzbq.sgj
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd fsqvbv
+$ ls
+114278 hwrhzs.jbj
+dir tvpzh
+$ cd tvpzh
+$ ls
+17235 gvmdvcs.fmq
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd wbssjjd
+$ ls
+dir mdjrhmhf
+$ cd mdjrhmhf
+$ ls
+11336 fqsp
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd ..
+$ cd spnr
+$ ls
+298067 sznwzj
\ No newline at end of file
diff --git a/input/day7_ex.txt b/input/day7_ex.txt
new file mode 100644
index 0000000..bcbb513
--- /dev/null
+++ b/input/day7_ex.txt
@@ -0,0 +1,23 @@
+$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k
\ No newline at end of file
diff --git a/src/day7.rs b/src/day7.rs
new file mode 100644
index 0000000..e0df644
--- /dev/null
+++ b/src/day7.rs
@@ -0,0 +1,132 @@
+use std::{collections::HashMap};
+
+// Making a recursive data structure in Rust is a pain in the ass.
+// So don't bother, just link one way (nodes own their children)
+// And we'll separately track our 'current working directory' with a 
+// vector of keys into the tree
+#[derive(Debug)]
+struct Node {
+    children: HashMap<String, Node>,
+    // Intrinsic size of the file at this location.
+    size: Option<u32>,
+    // Is the location a directory. Technically should be able to tell by presence/absence of children, but 
+    // empty directories are a thing.
+    isdir: bool,
+}
+
+impl Node {
+    fn new(isdir: bool) -> Node {
+        Node {
+            children: HashMap::new(),
+            size: None,
+            isdir: isdir,
+        }
+    }
+    fn set(&mut self, path: &Vec<&str>, size: Option<u32>, isdir: bool) {
+        let mut cn = self;
+        for ch in path {
+            cn = cn.children.entry((*ch).to_owned()).or_insert(Node::new(true));
+        }
+        cn.size = size;
+        cn.isdir = isdir;
+    }
+    /**
+     * Returns a map of total, recursive directory sizes,by relative path from the current directory
+     * Empty string key is the current directory size
+     */ 
+    fn dir_sizes(self) -> HashMap<String, u32> {
+        let mut res: HashMap<String, u32> = HashMap::new();
+        let mut mysize: u32 = 0;
+        for (name, nn) in self.children {
+            if let Some(fz) = nn.size {
+                // It's a file, just add the size
+                mysize += fz;
+            } else {
+                // It's a directory, add the size _and_ all the entries with subdir prefixed
+                let child_ds = nn.dir_sizes();
+                let child_sz = child_ds[""];
+                mysize += child_sz;
+                for (cn, sz) in child_ds {
+                    res.insert(format!("{}/{}", name, cn), sz);
+                }
+            }
+        }
+        res.insert("".to_owned(), mysize);
+        res
+    }
+}
+
+pub fn run(input: String) {
+    let mut root = Node::new(true);
+    let mut cwd: Vec<&str>= vec![];
+    let lines: Vec<&str> = input.lines().collect();
+    let mut i = 0;
+    loop {
+        if i >= lines.len() {
+            break;
+        }
+        let line = lines[i];
+        let toks: Vec<&str> = line.split_whitespace().collect();
+        if toks[0] != "$" {
+            panic!("expected a command, got {}",line);
+        }
+        match toks[1] {
+            "cd" => {
+                i += 1;
+                let dirname = toks[2];
+                if dirname == "/" {
+                    cwd.clear();
+                } else if dirname == ".." {
+                    cwd.pop();
+                } else {
+                    cwd.push(dirname);
+                }
+                root.set(&cwd, None, true);
+            }
+            "ls" => {
+                i += 1;
+                loop {
+                    if i >= lines.len() {
+                        break;
+                    }
+                    let lsline = lines[i];
+                    let lstoks: Vec<&str> = lsline.split_whitespace().collect();
+                    if lstoks[0] == "$" {
+                        // This is the next command, loop back to the top without incrementing!
+                        break;
+                    }
+                    let (fsize, isdir) = if lstoks[0] == "dir" {
+                        (None, true)
+                    } else {
+                        (Some(lstoks[0].parse().expect("filesize wasn't a u32!")), false)
+                    };
+                    let fname = lstoks[1];
+                    cwd.push(fname);
+                    root.set(&cwd, fsize, isdir);
+                    cwd.pop();
+                    i += 1;
+                }
+            }
+            cmd => {
+                panic!("unknown command {}", cmd)
+            }
+        }
+    }
+    let ds = root.dir_sizes();
+    // let mut tot: u32 = 0;
+    // for (_, sz) in ds {
+    //     if sz <= 100000 {
+    //         tot += sz;
+    //     }
+    // }
+    // println!("Day 7: {}", tot);
+    let fs_size:u32 = 70000000;
+    let total_used = ds.get("").unwrap();
+    let total_free = fs_size - total_used;
+    let update_size:u32 = 30000000;
+    let need_to_free = update_size - total_free;
+    let ddsz = ds.values()
+        .filter(|sz| { **sz >= need_to_free })
+        .fold(fs_size, |acc, e| { acc.min(*e) });
+    println!("Day 7: {}", ddsz);
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 0be4d7f..b370693 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,6 +6,7 @@ mod day3;
 mod day4;
 mod day5;
 mod day6;
+mod day7;
 
 fn main() {
     day1::run(fs::read_to_string("input/day1.txt").expect("Failed to read input file!"));
@@ -14,4 +15,5 @@ fn main() {
     day4::run(fs::read_to_string("input/day4.txt").expect("Failed to read input file!"));
     day5::run(fs::read_to_string("input/day5.txt").expect("Failed to read input file!"));
     day6::run(fs::read_to_string("input/day6.txt").expect("Failed to read input file!"));
+    day7::run(fs::read_to_string("input/day7.txt").expect("Failed to read input file!"));
 }