diff --git a/day11.py b/day11.py
new file mode 100644
index 0000000..da58184
--- /dev/null
+++ b/day11.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+
+# https://adventofcode.com/2025/day/11
+
+f = open("day11input.txt", "r")
+#f = open("testinput.txt", "r")
+
+graph = {}
+for line in f.readlines():
+  node, outputs = line.strip("\n").split(":")
+  graph[node] = outputs.strip().split(" ")
+
+
+def part1(current_path: list[str] | str, end: str) -> None:
+  if isinstance(current_path, str):
+    current_path = [current_path]
+  
+  node = current_path[-1]
+
+  # check for dead ends
+  if node not in graph.keys():
+    return
+
+  # check if end node is reachable from current node
+  if end in graph[node]:
+    found_paths.append(current_path + [end])
+    return
+  
+  # check all outputs
+  for output in graph[node]:
+    # avoid loops
+    if output in current_path:
+      continue
+    part1(current_path + [output], end)
+        
+
+
+def part2(start: str, end: str) -> int:
+  print(f"STARTING BACKWARDS SEARCH FROM {end} TO {start}")
+  num_paths = {end: 0}
+
+  def backsearch(target_node: str, current_node: str) -> int:
+    # init num_paths value for current node
+    num_paths[current_node] = 0
+
+    # find nodes with edges into current node
+    inputs = list(filter(lambda n: current_node in graph[n], graph.keys()))
+
+    # check if current_node is a dead end
+    if len(inputs) == 0:
+      return
+    
+    # loop over input nodes
+    for node in inputs:
+      # check if node is the target node
+      if node == target_node:
+        num_paths[current_node] = 1
+
+      # input node was visited already
+      elif node in num_paths.keys():
+        num_paths[current_node] += num_paths[node]
+
+      # input node was not yet visited
+      else:
+        backsearch(target_node, node)
+        num_paths[current_node] += num_paths[node]
+      
+    return
+
+  backsearch(start, end)
+  return num_paths[end]
+  
+
+
+
+# part 1
+found_paths = []
+part1("you", "out")
+print(len(found_paths))
+
+# part2
+svr2dac = part2("svr", "dac")
+print(svr2dac)
+dac2fft = part2("dac", "fft")
+print(dac2fft)
+fft2out = part2("fft", "out")
+print(fft2out)
+svr2fft = part2("svr", "fft")
+print(svr2fft)
+fft2dac = part2("fft", "dac")
+print(fft2dac)
+dac2out = part2("dac", "out")
+print(dac2out)
+
+print("final result:", svr2dac * dac2fft * fft2out + svr2fft * fft2dac * dac2out)
diff --git a/day11input.txt b/day11input.txt
new file mode 100644
index 0000000..d147a88
--- /dev/null
+++ b/day11input.txt
@@ -0,0 +1,647 @@
+dfa: nbz qhk kzw
+nzm: ors
+coh: hvt mrm yvu
+grm: jon
+jcu: dco reg
+hgd: zum ets rml
+yqr: gbd you dev oki
+zia: fft gpd
+wgs: mwd
+rma: smb
+pfh: jgr
+kva: wkb elg
+ggl: qcf hvt
+egb: hzs dwx
+nwk: out
+owz: nwk abc
+loe: adu roz vis
+qdw: npt you dev
+esy: pbj gyu nph jeh
+fdg: ykn epk jau
+piz: dxz jbc swk
+bby: pxp
+qcf: enj qhf sav siy tbn ccn
+req: ckp lew
+you: vhr jzm onn muy wsz pba nqx chd uvn fgl leo tvv ajb
+epk: gbd npt dev oki
+ttu: hzs dwx weu dsm
+ajb: knu
+zis: owr wie sdo
+baz: icr xxa
+wof: hht wwo hpk
+yde: aha acu gob
+ugq: bpa
+gxo: muw gcw dca kja
+cnf: swk
+kby: spx suh ats
+qgt: php zqq jva pkm
+oeh: huq ahv gun van
+osl: qcf hvt yvu
+hya: gob szv aha ors acu
+vlc: lfr vfm xsh
+hqt: ptd nid
+ifl: yvu qcf
+nba: ddz hsk are wkt
+gob: xsh vfm lfr
+ckc: zia tub
+biu: qrc
+ekm: wgs mit
+oki: jcu nqx mok uvn pph pfh ajb tvv vhr onn avk jzm vcb muy pba qvl chd ssk leo dnj nno fgl wqz vyw wsz
+ytg: isi thh csk
+fwt: xzk guu obh
+ivc: xog
+pkm: xxa icr
+wux: qcf yvu hvt mrm
+yjo: spx
+zqq: xxa ptd icr
+scc: xsh
+jbc: bby grt
+ssk: ugq rhm
+epo: bgi avt vrq
+hmi: awf
+uhe: xog ble
+dla: yaa shj
+hok: ryk anu qqm mag zes uhe ygh kaj jif syl dla qdf nle vao udl dvq xil
+ors: lfr dhl xsh
+vrt: xsh lfr
+onn: wfl
+xhi: smb
+wol: nqc fga frw
+mfc: wyu hhq
+uku: obh xzk wcz
+vyw: ekm
+tmh: mrm
+lfr: lvh dly ibi yee ywp ksa ogz rog zph fks nnp qnp zsg drv
+vhh: dhl
+rhb: jur cgb
+ovf: dln bvr
+azm: vzw yfz osl bmb
+ken: vso ybh ifl ofa
+for: scc icp
+fuj: nmg zia dls
+scb: ijp ekw
+lme: mod ygu
+cev: til yox axf
+fks: red qip sda
+szv: vfm dhl xsh
+ygf: vnf xvj hgd
+ygu: icr ptd xxa
+zzz: qbf kik
+weh: out
+ljf: xvj ybc
+php: ptd nid
+wsx: rgq
+wnb: snh wct
+suh: vfm
+are: ilu
+qec: yuj lwk tso
+uys: vip
+guu: out
+nkj: loi jfl ejf
+ddw: asd yot owz
+tid: bgi qzw xiv
+dmu: kgk gxo ebz yaa
+ptd: der inq jwg piz klp qag mtj yyf emp foa fgy ift zii lwe ddd gbz
+qhv: dfd tnj vkj
+nmv: mwb vkj dfd
+isi: uba izt mdn xhi
+jau: npt gbd oki
+bhg: vas rnl ora pnt
+mcg: otw mfq
+wkr: dev oki npt gbd
+vis: oih
+kzw: jur
+wwo: ivg acz
+ykn: you oki dev
+oen: hvt
+dsu: ytg cim
+kzx: byq few btc rrz
+mrm: qgx tbn dsu kbc ccn rci crh neh wnb enj sav xur mfc azx qgu qiq qhf apg siy
+ucs: ead rhb
+swk: grt bby
+nvu: hvt qcf
+jon: vhh vlc
+few: out
+vgb: lfr dhl xsh
+gdd: hvt yvu
+osi: jvm zmz ddw
+thh: izt rma uba
+dys: wbu ucs bpf
+vso: hvt mrm qcf
+npt: wqz fgl nno dnj leo ssk chd wsz vyw tvv ajb pfh pph uvn mok jcu nqx biu qvl pba muy vcb jzm avk onn vhr
+dac: epk kbw jau
+izj: mea hmi
+qrc: jxk epv
+vaf: qgt
+ddd: bhg bcj
+pph: jgr rhm ugq
+nfh: qmt csk thh
+qdf: hyp
+ets: out
+xgk: dhl xsh
+boa: hpk hht
+ppr: wof
+ble: lht ugz bpr
+dyg: qmt
+dca: cpe eyi
+hjm: nep yya kik
+zes: hyp uzy
+vgl: hfm
+vkp: mgv iah
+vsh: cts xtl xsp
+rrz: out
+ckp: hsk ddz kqe
+mxe: yuj
+tre: luh
+paz: wwo
+luh: wcg
+bvv: vxi etm
+qzw: fri
+hht: vgl yjo acz kby
+itk: sdc alv tjv
+xyo: hpz axf yox yyn
+xkh: hhq zdi wyu qix
+kgk: muw
+mit: fsf mvk mwd
+qse: lqt lxh wil
+ofa: hvt mrm yvu qcf
+ior: icr ptd nid xxa
+syz: duo
+vrq: rxb pfk fri
+snh: hyg nop vaf sgh
+csk: uba rma izt mdn xhi
+dpw: jur zod
+xwy: lsk bbi
+mvk: tlo itk juq
+wbu: rhb
+otw: loi tcv
+gpd: vrt scc
+xog: ugz lht bpr bvv
+nbr: byq few
+hzt: wsx fms
+sda: tdh bye eif ggl
+byq: out
+gbd: uvn pph mok jcu nqx ajb tvv pfh onn avk jzm vhr pba qvl biu vcb muy chd ssk wqz leo nno dnj vyw wsz
+rhj: paz
+kaj: dfa zzp jky ost
+zsg: rwo sqf xyg
+reg: hoi epv
+oee: bne
+jha: gyu jeh
+chd: wfl
+yyf: poh zzz hjm
+wil: ahz
+dfd: oki you gbd npt
+mfj: bgi vrq xiv
+fri: vyd
+qvl: jgr
+oyd: vfm lfr dhl
+smg: oki dev you gbd
+bco: amy kzx
+ats: dhl vfm
+cqs: lfr
+tzw: oen gnu qxh gdd
+rwc: mrp jbc
+iwx: qlz bss awf
+dnj: reg qrc dco
+ibi: vrm elg
+dly: ykj qip sda
+jur: izj hfj tid epo ckc gwu eei syz tlb
+ast: php jva zqq uxg
+rnl: ngy eiq
+zzp: kzw hed lfk qhk
+nkp: tnj vkj
+viz: mvk
+hpz: ptd
+qip: eif bye
+rwo: pth
+mwb: gbd npt
+qiq: vsh vca
+prl: kzw lfk qhk
+flo: dhl lfr
+lkz: hhx
+siy: sce
+xtl: xlz guz
+kgu: qtw ura wkr smg bwf
+uun: out
+gyu: ldh ttu
+nep: mfq gvg
+bpr: qec etm mxe
+ltr: gbd npt oki dev
+svr: yxc gwm hok
+avk: sdn zpz vvt zhw
+xyg: krb wcg
+boh: nmv qhv nkp
+rgo: jdt rhb ead
+jva: xxa nid
+tni: nmg tub zia dls
+nei: vfm
+izd: mvp kgx scb sjc
+qpy: rwo sqf
+qtw: dev oki
+izt: lrw baz smb
+jdt: zod cgb jur
+ewt: iwx mea auv
+lwe: bcj
+qag: sjc
+hgv: osi bws hhx
+sce: sdo
+cts: guz hqt
+vzw: hvt mrm qcf
+lrw: nid icr xxa
+ivg: fzd suh spx
+gun: tzw eia
+ebz: muw kja
+abc: out
+apg: lkf vsh sif
+xlz: xxa nid ptd icr
+see: bmi
+sdn: bsl rob
+cai: van huq
+lrg: qtw bwf wkr smg
+vsy: gfb weh uun
+acu: vfm xsh
+bwf: gbd npt you dev oki
+sdo: nid ptd xxa
+mfp: qip
+dls: gpd fft
+nsc: ivf
+vhr: mxw dco
+ldh: dpw hzs weu
+vwg: paz
+yfz: hvt
+rci: nfh dyg nqt
+bbi: qcf mrm yvu
+xkj: weh
+juq: tjv alv sdc
+kqe: gik clq ilu
+jxk: bco
+inq: zzz hjm poh
+nqx: ekm aet uyh
+blj: ior mod rgi
+udl: jha var esy vqa zex
+mok: vvt sdn
+fsf: juq tlo hgf
+qwi: mwb dfd
+ora: ngy eiq
+sav: zis mbp
+axf: nid ptd
+kik: otw
+cxl: azm
+nbz: jur
+zmz: vkp okc owz
+zum: out
+eei: boa paz
+nhm: uun gfb
+shj: gcw
+sow: lsk
+byv: ybh ofa
+anu: isj xog
+tso: zod jur cgb
+xdr: osl vzw
+jky: hed kzw qhk nbz
+klc: xdr fol
+vas: eiq gys
+ykj: bye tdh
+dsm: zod jur cgb
+van: tzw azs fkq
+rux: bby grt mgw
+nnp: vrm wkb elg
+klp: kgx scb
+pth: coh jpj nvu wmz tmh
+ekw: fga frw
+xsh: fks mfp vlq kva kqb gtw drv qnp
+hyp: fvp nba lew
+hde: bvv bpr ugz
+weu: jur
+nmg: gpd
+yvu: crh ruf rci ccn xkh kbc dsu qgx tbn sav enj wnb neh azx mfc xur siy apg qhf qiq qgu
+nno: zpz zhw vvt
+gwu: dln bvr
+vlq: sqf rwo
+lxh: ahz lme blj
+bcj: vas
+kgx: ggc ekw wol
+tus: pkm php jva zqq
+fft: icp ymx vrt vgb scc
+ahv: eia azs tzw fkq
+hgf: esi tjv
+dhl: tre ibi fks lvh qpy cai kqb oeh ywp
+vcb: reg qrc dco mxw
+yuj: jur cgb
+emp: mvp
+nbj: obh wcz eot
+muw: mao cpe eyi ybf
+nvy: vso ifl ybh
+yvt: ljf llb eoc
+auv: dxq qlz awf
+jns: ucs
+smb: ptd
+icp: lfr vfm dhl
+lvh: vrm
+wct: hyg nop vaf
+foa: fms
+gik: jur zod
+ugz: etm
+hhq: dog xzr bne xyo
+qdc: eoc
+pnt: gys ngy
+hed: zod
+acz: fzd
+lqt: lme ahz
+ujd: qwi
+xiy: vso ybh ifl
+qlz: oyd nei cqs
+ssl: yvu
+jeh: egb ttu ldh
+wkw: vlc
+ubb: guz hqt
+dev: onn wsz vcb biu mok ssk uvn chd fgl nno dnj leo
+vca: xsp xtl cdb ubb
+uvn: zpz zhw vvt
+zph: zok yvz
+pyk: vhh
+hsk: clq gik
+kja: ybf cpe mao
+jgr: wkf bjz bpa yvt
+der: nkp
+kbw: dev you
+fkq: gdd qxh gnu
+ijq: sgh vaf
+dgy: uxg jva
+bss: wfz flo oyd
+avt: fri pfk grm rxb
+bne: axf
+yya: nkj
+xur: sce mbp
+mxw: hoi epv
+qhd: lxh
+eot: out
+rml: out
+huq: fkq azs tzw
+ost: hed kzw qhk nbz
+fgy: scb
+jif: xog isj hde
+azx: dyg cim nfh ytg
+wqz: wfl loe
+uxg: nid xxa
+zok: lsk bbi
+fbt: uun gfb
+xiv: hsb
+icr: pyl inq cnf boh hzt gbz klp piz aoz pkd
+qbf: nkj otw mfq
+qmt: uba
+rgq: gys
+bpf: jdt
+llb: vnf ybc
+vvt: bsl
+gys: you oki gbd npt
+yyn: ptd nid xxa
+adu: oih
+owr: nid icr ptd xxa
+xil: hde ble
+ybc: rml ets zum
+cdb: xlz hqt guz
+rva: guu obh wcz
+yvz: wux
+mkh: fwt nbj
+gtd: xgk vlc
+vkj: oki dev gbd
+qhf: zis
+fka: adu uys vis
+til: ptd icr xxa
+pkd: bhg wsx bcj
+jzm: aet ekm
+jbt: req
+knu: hhx bws
+syl: zex esy var jha
+clq: cgb
+qix: xyo xzr cev
+yee: xwy sow zok
+zdi: dog
+ddz: gik clq
+qhk: cgb jur
+tbn: qhd qys qse
+vfm: qpy fks zph ogz nnp oeh qnp gtw drv lvh ibi dly ywp yee cai
+bjz: eoc ljf llb
+xpa: njk nbr hcw
+lus: eia
+dln: hya
+uba: lrw
+iah: out
+mfq: ltr ejf
+ura: dev you npt
+ygh: zzp dfa prl ost
+sif: xtl xsp cts cdb ubb
+nid: der jwg pyl inq klp piz izd pkd boh hzt emp mtj qag fgy see foa rwc lwe aoz ift gbz ddd
+fga: yqr qdw caw uud
+ift: qhv nkp
+dfi: gfb weh
+ogz: sow zok xwy yvz
+pfk: wkw pyk jon gtd
+alv: out
+leo: fka
+fzd: xsh lfr vfm
+uyh: wgs viz mit
+vxi: tso lwk
+wkf: ygf eoc ljf
+ywp: lus
+loi: you oki dev
+bsl: mkh jmw
+qys: lxh
+xzr: yyn hpz axf yox
+spx: xsh
+mbp: owr wie
+wkt: gik
+qgu: ijq
+rhm: bjz wkf qdc
+gvg: ltr tcv jfl loi
+obh: out
+bpa: llb ygf
+oih: nhm dfi vsy
+ymx: vfm lfr xsh
+lsk: yvu
+nqt: isi qmt
+hcw: few rrz btc
+wcz: out
+sqf: wcg pth krb
+ruf: wct ijq snh
+tdh: qcf hvt yvu
+rob: mkh ivf
+wcg: jpj nvu wmz coh
+fvp: ddz kqe are
+eoc: xvj
+sdc: out
+saq: fol
+lkf: xsp xtl cts ubb
+muy: aet ekm
+ijp: fga
+grt: lrg
+poh: qbf kik mcg
+nph: ttu
+ryk: zex
+qnp: cxl
+zii: swk mrp jbc rux
+jvm: asd owz
+etm: lwk tso yuj
+hoi: bco xpa kqt
+duo: yde nzm
+bmi: epk
+azs: gdd qxh
+zod: tni hfj rhj ewt pma dbc syz fuj gwu epo vwg
+dxq: oyd nei cqs flo wfz
+lcw: kbw epk jau
+gcw: cpe
+hpk: yjo kby vgl ivg
+nqc: qdw uud yqr
+mdn: lrw smb baz
+hhx: jvm zmz
+sxj: out
+hvt: dsu qiq nvm apg ruf
+dwx: jur zod
+pba: hgv lkz
+tnj: npt gbd dev oki you
+esa: yya mcg
+jmw: uku nud nbj
+isj: bvv lht
+ybf: jur
+eyi: jur cgb zod
+hyg: scl tus
+wmz: yvu qcf
+bye: qcf yvu mrm
+red: ggl eif tdh ssl
+ggc: nqc
+fym: gxo shj kgk ebz
+mgv: out
+tlo: esi tjv
+lwk: zod
+aoz: zzz hjm esa poh
+gwm: anu ryk dmu qqm uhe zes dys jif kaj jbt qdf dla jns dvq fym vao ivc udl
+gtw: vrm wkb
+sgh: tus dgy
+ilu: zod jur cgb
+dbc: iwx hmi
+ybz: lxh wil
+xvj: zum
+hfj: zia
+krb: nvu
+vqa: pbj nph
+yaa: muw kja dca gcw
+elg: ken byv
+btc: out
+hsb: gtd vyd pyk
+scl: jva
+jwg: bmi fdg lcw dac
+bvr: yde hya
+cgb: fuj vwg ban tlb eei dbc syz ovf pma hfj ndm ckc gwu tid epo mfj ewt izj ppr rhj tni
+hzs: cgb
+rxb: vyd wkw jon gtd
+awf: nei wfz flo
+ahz: rgi mod ygu
+kqt: hcw amy njk
+cim: csk thh
+vnf: ets
+bmb: qcf
+nvm: ybz qhd
+mtj: dac lcw bmi
+caw: npt
+njk: btc rrz few byq
+mea: qlz
+rgi: icr
+ejf: you gbd npt
+ivf: rva uku nbj
+lfk: zod jur cgb
+bnb: nhm fbt
+mwd: juq hgf
+vip: xkj vsy nhm
+pxp: qtw bwf ura wkr smg
+mrp: bby mgw
+qgx: hhq oee qix
+wfz: xsh
+ybh: hvt mrm
+tjv: out
+kbc: sif vca vsh lkf
+eia: gnu gdd
+xxa: jwg ujd pyl inq boh piz izd pkd fgy foa emp yyf mtj qag gbz ddd aoz ift zii
+gnu: qcf mrm
+aha: vfm xsh
+pbj: ldh ttu
+neh: oee wyu qix hhq
+fms: rnl
+gbz: poh zzz
+wkb: nvy ken byv xiy
+tcv: gbd npt oki dev you
+uud: you oki dev npt gbd
+asd: nwk abc
+pma: tub
+nop: scl dgy qgt ast
+ead: zod
+utv: owz yot okc asd
+tub: fft gpd for
+esi: out
+nud: eot
+roz: vip bnb
+bgi: grm fri
+nle: zex vqa
+eiq: dev you
+jpj: hvt qcf
+yot: abc iah mgv
+zex: jeh gyu pbj
+ndm: dln duo
+zhw: pka
+wyu: xzr
+qqm: req hyp uzy
+epv: kqt
+dco: epv
+qxh: qcf hvt mrm yvu
+tlb: wof paz boa
+dvq: jha zex esy
+wie: ptd
+yox: icr
+ksa: van gun ahv huq
+skr: mrm hvt
+mao: cgb
+ban: auv mea hmi
+frw: uud qdw
+vao: prl zzp dfa
+zpz: rob bsl nsc pka
+vyd: xgk
+eif: mrm yvu qcf
+cpe: zod jur
+aet: viz
+enj: snh
+dxz: mgw
+mvp: ekw wol ggc
+var: nph gyu
+mgw: lrg pxp kgu
+lht: vxi qec etm
+mag: ucs wbu rgo
+pyl: nkp qwi nmv
+drv: klc cxl saq
+mod: nid icr xxa
+amy: rrz byq
+dog: yox
+wfl: vis uys
+bws: utv jvm
+wsz: ekm uyh
+tvv: wfl
+yxc: ryk dmu anu qqm uhe mag jbt jif qdf jns ivc fym dvq nle xil
+hfm: vfm lfr dhl
+crh: qse qys
+kqb: cxl saq
+okc: sxj iah mgv abc
+fol: skr yfz osl
+xsp: xlz guz
+sjc: ekw ijp
+pka: mkh ivf jmw
+rog: zok xwy yvz
+guz: xxa ptd icr
+ngy: dev oki you npt gbd
+xzk: out
+gfb: out
+fgl: lkz knu hgv
+vrm: nvy xiy
+jfl: gbd npt oki you
+ccn: qse
+lew: ddz
+uzy: lew ckp nba