• Log InLog In
  • Register
Liquid`
Team Liquid Liquipedia
EDT 05:37
CEST 11:37
KST 18:37
  • Home
  • Forum
  • Calendar
  • Streams
  • Liquipedia
  • Features
  • Store
  • EPT
  • TL+
  • StarCraft 2
  • Brood War
  • Smash
  • Heroes
  • Counter-Strike
  • Overwatch
  • Liquibet
  • Fantasy StarCraft
  • TLPD
  • StarCraft 2
  • Brood War
  • Blogs
Forum Sidebar
Events/Features
News
Featured News
Team Liquid Map Contest #22: Results and Winners7Code S Season 2 (2026): RO4 and Finals Preview12TL.net Map Contest #22 - Voting & Ladder Map Selection7Code S Season 2 (2026) - RO8 Preview8[ASL21] Finals Preview: Two Legacies21
Community News
ZeroSpace at Steam NextFest - Last free demo20Weekly Cups (June 8-14): Clem and Solar double, PTR tested0RSL: S6 Finals played at BlizzCon 202611Douyu Cup 2026: $20,000 Legends Event (June 26-28)12[BSL22] Non-Korean Championship from 13 to 28 June4
StarCraft 2
General
StarCraft II 5.0.16 PTR Patch Notes may 26th Is the larve respawn broken? Yamato Cup Series What kind of tool would you be interested in? Daily SC2 Player Grid - feedback wanted
Tourneys
Douyu Cup 2026: $20,000 Legends Event (June 26-28) GSL CK #4 20-21th June Sparkling Tuna Cup - Weekly Open Tournament Master Swan Open (Global Bronze-Master 2) Crank Gathers Season 4: BW vs SC2 Team League
Strategy
[G] Having the right mentality to improve
Custom Maps
Work In Progress Melee Maps [D]RTS in all its shapes and glory <3
External Content
The PondCast: SC2 News & Results Mutation # 531 Experimental Artillery Mutation # 530 One For All Mutation # 529 Opportunities Unleashed
Brood War
General
BGH Auto Balance -> http://bghmmr.eu/ STARCRAFT MOVIE - Last Night at the Command center BW General Discussion Battle cruiser feet vs Carrier fleet Fact based Zerg Upgrade Tier List
Tourneys
CSLAN 4 is Coming! [Megathread] Daily Proleagues Small VOD Thread 2.0 The Casual Games of the Week Thread
Strategy
Why doesn't anyone use restoration? Simple Questions, Simple Answers Relatively freeroll strategies Creating a full chart of Zerg builds
Other Games
General Games
Stormgate/Frost Giant Megathread Path of Exile Beyond All Reason ZeroSpace at Steam NextFest - Last free demo Nintendo Switch Thread
Dota 2
Looking for a Dota Mentor Official 'what is Dota anymore' discussion
League of Legends
Heroes of the Storm
Simple Questions, Simple Answers Heroes of the Storm 2.0
Hearthstone
Deck construction bug
TL Mafia
Vanilla Mini Mafia
Community
General
US Politics Mega-thread Russo-Ukrainian War Thread [H]Internet/Gaming Cafe Tips and Tricks The Games Industry And ATVI UK Politics Mega-thread
Fan Clubs
The HerO Fan Club! The herO Fan Club!
Media & Entertainment
Movie Discussion! [Req][Books] Good Fantasy/SciFi books [TV/BOOK] *SPOILERS* Game of Thrones Discussion
Sports
2024 - 2026 Football Thread McBoner: A hockey love story TeamLiquid Health and Fitness Initiative For 2023 Formula 1 Discussion Cricket [SPORT]
World Cup 2022
Tech Support
Computer Build, Upgrade & Buying Resource Thread Facing Challenges in Mobile App Development
TL Community
The Automated Ban List
Blogs
How To Predict Tilt in Espor…
TrAiDoS
An Exploration of th…
waywardstrategy
I'm an arrogant trash talke…
FlaShFTW
Gauntlet SC2: A Retrospectiv…
Ctone23
Why RTS gamers make better f…
gosubay
Customize Sidebar...

Website Feedback

Closed Threads



Active: 7687 users

really interesting puzzle, took me a while!

Blogs > DoctorHelvetica
Post a Reply
1 2 Next All
DoctorHelvetica
Profile Blog Joined July 2008
United States15034 Posts
October 31 2009 11:34 GMT
#1
[image loading]


Try to come up with a solution to this puzzle, it took me a really long time to figure out. It's a good one.

Solution: + Show Spoiler +
C knows his hat is black, if his hat was white then D would have seen two white hats and yelled that his hat was black. Because D did not do this, C realized that D must be seeing 2 different hats and that his hat is therefore black.


*****
RIP Aaliyah
writer22816
Profile Blog Joined September 2008
United States5775 Posts
October 31 2009 11:54 GMT
#2
Great puzzle!
8/4/12 never forget, never forgive.
madnessman
Profile Blog Joined May 2009
United States1581 Posts
Last Edited: 2009-10-31 12:25:29
October 31 2009 12:11 GMT
#3
damn i'm really tempted to look at the solution. i've been staring at the diagram and instructions for like 5 minutes and i haven't figured it out yet.

EDIT: I GOT IT!
+ Show Spoiler +
If B and Cs hats are the same color D knows that his hat is obviously the other color and can call it out. If D does not call out a color C knows his hat is a different color than the guy in front of him and can call it out.


Here is another "guess the hat" brain teaser. This time there are 10 guys buried in the ground in a line. They are all facing forward so guy #1 can see everybody's hat (but his), guy #2 can see 3-10, guy #3 can see 4-10, etc... They each have a 50/50 chance of getting either a black or white hat (so it's not necessarily 5 x black and 5 x white). They all have to guess the color of their hat. Guy #1 guesses first, guy #2 guesses second, etc...

They have time before the test to agree on a strategy. There is a strategy which will save at least 9/10 guys for sure. What is it?

This isn't a trick question. They can't give audio clues like making your guess in a high pitch or a low pitch to tell the person in front of them what hat color they have. It's a logic/math solution.
Flicky
Profile Blog Joined December 2008
England2672 Posts
October 31 2009 12:13 GMT
#4
I hate when these puzzles make me feel slow.

To those working it out, this is completely logical. There is no trickery at all. I know the picture says it, but it's easy to doubt that. There's nothing like "he leans forward and the hat falls off".
Liquipedia"I was seriously looking for a black guy" - MrHoon
HwangjaeTerran
Profile Blog Joined October 2009
Finland5967 Posts
October 31 2009 12:21 GMT
#5
A knows he has got a black hat
no way they could´ve chosen a guy with white hat to be alone on the other side of the wall.
https://steamcommunity.com/id/*tlusernamehere*/
Ganfei
Profile Blog Joined August 2008
Taiwan1439 Posts
October 31 2009 12:22 GMT
#6
There are a lot of variations of this puzzle, I did a similar one back in one of my logic classes during freshman year of college. The part that irks me is that your answer relies on your compatriots (the other hat wearers) not being idiots. So that's kind of out of the question in a normal situation.
You are crushing me like a cheese sandwich
underscore
Profile Joined August 2009
252 Posts
October 31 2009 12:29 GMT
#7
Puzzles like this make we want to be an executioner. Even if they solve it I still shoot them then go home with a big smile on my face and plow my wife.
LordWeird
Profile Blog Joined November 2007
United States3411 Posts
October 31 2009 12:44 GMT
#8
This was quite simple but very fun. D would have noticed if he had seen two white hats and would have called out (if he had a brain in him). When C realized that D had not called out he figured he must have had the black hat.
Chains none
Phrogs!
Profile Blog Joined August 2008
Japan521 Posts
October 31 2009 14:13 GMT
#9
Kinda simple but fun. You have a site you got this from? I wanna keep going
Zinbiel
Profile Joined October 2008
Sweden878 Posts
October 31 2009 14:55 GMT
#10
On October 31 2009 21:11 madnessman wrote:
damn i'm really tempted to look at the solution. i've been staring at the diagram and instructions for like 5 minutes and i haven't figured it out yet.

EDIT: I GOT IT!
+ Show Spoiler +
If B and Cs hats are the same color D knows that his hat is obviously the other color and can call it out. If D does not call out a color C knows his hat is a different color than the guy in front of him and can call it out.


Here is another "guess the hat" brain teaser. This time there are 10 guys buried in the ground in a line. They are all facing forward so guy #1 can see everybody's hat (but his), guy #2 can see 3-10, guy #3 can see 4-10, etc... They each have a 50/50 chance of getting either a black or white hat (so it's not necessarily 5 x black and 5 x white). They all have to guess the color of their hat. Guy #1 guesses first, guy #2 guesses second, etc...

They have time before the test to agree on a strategy. There is a strategy which will save at least 9/10 guys for sure. What is it?

This isn't a trick question. They can't give audio clues like making your guess in a high pitch or a low pitch to tell the person in front of them what hat color they have. It's a logic/math solution.

This works, right?
+ Show Spoiler +
If they agree that number 1 will guess white if he sees an odd number of white hats and guess black if he sees an even number of white hats. If number 1 calls white and number 2 sees an even number of white hats he's got a white one. If he sees an odd number he's got a black one. Rinse and repeat, everyone have to remember when it's there turn if they should have an even or odd number of whites in front of them.
Backho fan since 080416. Favourite terran: Mind. Favourite Zerg: Jaedong.
Thats_The_Spirit
Profile Blog Joined April 2009
Netherlands138 Posts
October 31 2009 14:56 GMT
#11
Nice puzzle
Adeny
Profile Blog Joined January 2009
Norway1233 Posts
October 31 2009 16:09 GMT
#12
There's actually no correct answer to OP's puzzle, not even his own answer. + Show Spoiler +
Just because D sees 2 different colors doesn't mean that D's hat has to be white. For all he knows, A and C has white, B and D has black. Unfortunately your hat-men are left with a 50-50 guess for whomever is feeling lucky that day.
JeeJee
Profile Blog Joined July 2003
Canada5652 Posts
Last Edited: 2009-10-31 16:18:26
October 31 2009 16:15 GMT
#13
iv seen far too many of these puzzles this one took me no time at all :p
+ Show Spoiler +

well C can see a white hat and i assume he knows that D can see both his and B's hats. therefore C knows that D sees a white + X. if D sees white+white, he'd auto-yell black. he doesn't, because he sees white+black. C realizes this and since he's not the white (cos he can see the white) he's sure he's black


also @adeny
+ Show Spoiler +

what? D's color doesn't matter, he's not the one guessing, because like you said, he can't be sure of his color cos he sees diff ones. C is the one guessing and C knows his color 100% given 2 conditions:
-he knows that D can see B and C's hats
-D is not an idiot
(\o/)  If you want it, you find a way. Otherwise you find excuses. No exceptions.
 /_\   aka Shinbi (requesting a name change since 27/05/09 ☺)
Zinbiel
Profile Joined October 2008
Sweden878 Posts
Last Edited: 2009-10-31 16:16:27
October 31 2009 16:15 GMT
#14
On November 01 2009 01:09 Adeny wrote:
There's actually no correct answer to OP's puzzle, not even his own answer. + Show Spoiler +
Just because D sees 2 different colors doesn't mean that D's hat has to be white. For all he knows, A and C has white, B and D has black. Unfortunately your hat-men are left with a 50-50 guess for whomever is feeling lucky that day.

You don't seem to understand.

+ Show Spoiler +
Your scenario doesn't matter, since it isn't D who are the one with the information he needs to tell what color his hat is, it is C. C sees that B has a white hat. The fact that D doesnt cry out tells C that he and B has different colors and since he sees that B has a white one, hence his hat is black. If he had seen a black hat in front of him and no reaction from D, he would have a white hat.
Backho fan since 080416. Favourite terran: Mind. Favourite Zerg: Jaedong.
kerpal
Profile Blog Joined June 2009
United Kingdom2695 Posts
October 31 2009 16:34 GMT
#15
On October 31 2009 21:22 NoobsOfWrath wrote:
There are a lot of variations of this puzzle, I did a similar one back in one of my logic classes during freshman year of college. The part that irks me is that your answer relies on your compatriots (the other hat wearers) not being idiots. So that's kind of out of the question in a normal situation.


puzzle should say, "this diagram shows 4 puzzle nerds buried up to their necks in sand"
-orb-
Profile Blog Joined September 2007
United States5770 Posts
October 31 2009 16:51 GMT
#16
I don't like this one because + Show Spoiler +
it relies on D not being a retard. If I was C in that situation I would be scared as fuck to say my hat was black because I'd be worried D was just a dumbfuck tool and he didn't know what he was doing lol
'life of lively to live to life of full life thx to shield battery'
how sad that sc2 has no shield battery :(
ejac
Profile Blog Joined January 2009
United States1195 Posts
October 31 2009 17:04 GMT
#17
This seemed hard at first, but I figured it out in less than a minute.
esq>n
Pengu1n
Profile Blog Joined October 2004
United States552 Posts
October 31 2009 17:09 GMT
#18
On November 01 2009 01:51 -orb- wrote:
I don't like this one because + Show Spoiler +
it relies on D not being a retard. If I was C in that situation I would be scared as fuck to say my hat was black because I'd be worried D was just a dumbfuck tool and he didn't know what he was doing lol



This is why its just a fun logic puzzle. If it were a real live situation I think even the smartest people when trapped up to their necks so they can't move and are about to be executed would panic and lose most of their logical reasoning. Doesn't necessarily make them "dumbfuck retarded tools".

However if this was a real life situation where there was no penalty or execution, just a 10 min time limit and people buried in the sand with hats just to try to figure out the riddle, then maybe it would be fair to call them dumb ;p
revolover
Profile Joined January 2009
Canada134 Posts
October 31 2009 17:36 GMT
#19
Great problem!
Dr.Lettuce
Profile Blog Joined September 2008
United Kingdom663 Posts
Last Edited: 2009-10-31 17:54:34
October 31 2009 17:54 GMT
#20
damn just spent half an hour on this.
I think the answer is C.
Because he knows B's hat is white. D would then have called out his hat was black, if C was white as well. However he didn't call out. Meaning he can see one white and black hat. Since B's is white. C can be 100% certain his hat is black?

haha yes! that was damn satisfying
1 2 Next All
Please log in or register to reply.
Live Events Refresh
Next event in 1h 23m
[ Submit Event ]
Live Streams
Refresh
StarCraft 2
SortOf 90
StarCraft: Brood War
Larva 1652
Pusan 240
Soma 228
Killer 216
Hyuk 210
actioN 188
Leta 133
Dewaltoss 75
Sharp 48
Hm[arnc] 43
[ Show more ]
HiyA 34
Noble 24
sorry 24
NaDa 21
soO 14
firebathero 0
Light 0
Dota 2
Gorgc2716
XcaliburYe11
League of Legends
JimRising 481
Counter-Strike
shoxiejesuss905
Other Games
ceh9766
Pyrionflax184
crisheroes92
KnowMe81
Organizations
Dota 2
PGL Dota 2 - Secondary Stream4845
PGL Dota 2 - Main Stream3306
Other Games
gamesdonequick828
StarCraft 2
Blizzard YouTube
StarCraft: Brood War
BSLTrovo
[ Show 16 non-featured ]
StarCraft 2
• LUISG 33
• AfreecaTV YouTube
• intothetv
• Kozan
• IndyKCrew
• LaughNgamezSOOP
• Migwel
• sooper7s
StarCraft: Brood War
• iopq 7
• BSLYoutube
• STPLYoutube
• ZZZeroYoutube
League of Legends
• Jankos1765
• Rush1297
• Stunt611
• HappyZerGling112
Upcoming Events
WardiTV Weekly
1h 23m
Monday Night Weeklies
6h 23m
Sparkling Tuna Cup
1d
The PondCast
2 days
Douyu Cup 2020
2 days
Oliveira vs Trap
Jieshi vs XY
soO vs FanTaSy
TY vs Coffee
Douyu Cup 2020
3 days
Neeb vs Impact
MacSed vs Cyan
Scarlett vs Kelazhur
INnoVation vs Dear
Douyu Cup 2020
4 days
Maestros of the Game
5 days
herO vs Classic
Maru vs Serral
BSL22 NKC (BSL vs China)
5 days
Douyu Cup 2020
5 days
[ Show More ]
BSL22 NKC (BSL vs China)
6 days
Online Event
6 days
RSL Revival
6 days
Liquipedia Results

Completed

Acropolis #4
WardiTV Spring 2026
Heroes Pulsing #2

Ongoing

IPSL Spring 2026
CSCL: Masked Kings S4
YSL S3
BSL 22 Non-Korean Championship
CSL Season 21: Qualifier 1
SCTL 2026 Spring
Maestros of the Game 2
Murky Cup 2026
IEM Cologne Major 2026
Stake Ranked Episode 2
CS Asia Championships 2026
Asian Champions League 2026
IEM Atlanta 2026
PGL Astana 2026
BLAST Rivals Spring 2026
IEM Rio 2026
PGL Bucharest 2026

Upcoming

CSL Season 21: Qualifier 2
CSL 2026 Summer (S21)
CSLAN 4
Blizzard Classic Cup 2026
Kung Fu Cup 2026 Grand Finals
RSL Revival: Season 6
CranK Gathers Season 4: BW vs SC2 Team League
HSC XXIX
Douyu Cup 2026
BCC 2026
Light HT
Heroes Pulsing #3
BLAST Open Fall 2026
Esports World Cup 2026
BLAST Bounty Summer 2026
BLAST Bounty Summer Qual
Stake Ranked Episode 3
XSE Pro League 2026
TLPD

1. ByuN
2. TY
3. Dark
4. Solar
5. Stats
6. Nerchio
7. sOs
8. soO
9. INnoVation
10. Elazer
1. Rain
2. Flash
3. EffOrt
4. Last
5. Bisu
6. Soulkey
7. Mini
8. Sharp
Sidebar Settings...

Advertising | Privacy Policy | Terms Of Use | Contact Us

Original banner artwork: Jim Warren
The contents of this webpage are copyright © 2026 TLnet. All Rights Reserved.