• Log InLog In
  • Register
Liquid`
Team Liquid Liquipedia
EDT 23:05
CET 04:05
KST 12:05
  • 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 - Presented by Monster Energy5ByuL: The Forgotten Master of ZvT30Behind the Blue - Team Liquid History Book19Clem wins HomeStory Cup 289HomeStory Cup 28 - Info & Preview13
Community News
Blizzard Classic Cup @ BlizzCon 2026 - $100k prize pool30Weekly Cups (March 9-15): herO, Clem, ByuN win42026 KungFu Cup Announcement6BGE Stara Zagora 2026 cancelled12Blizzard Classic Cup - Tastosis announced as captains18
StarCraft 2
General
Potential Updates Coming to the SC2 CN Server Weekly Cups (March 2-8): ByuN overcomes PvT block Weekly Cups (August 25-31): Clem's Last Straw? Weekly Cups (March 9-15): herO, Clem, ByuN win Blizzard Classic Cup @ BlizzCon 2026 - $100k prize pool
Tourneys
RSL Season 4 announced for March-April Sparkling Tuna Cup - Weekly Open Tournament WardiTV Team League Season 10 KSL Week 87 [GSL CK] #2: Team Classic vs. Team Solar
Strategy
Custom Maps
Publishing has been re-enabled! [Feb 24th 2026]
External Content
The PondCast: SC2 News & Results Mutation # 517 Distant Threat Mutation # 516 Specter of Death Mutation # 515 Together Forever
Brood War
General
BGH Auto Balance -> http://bghmmr.eu/ ASL21 General Discussion Gypsy to Korea JaeDong's form before ASL BSL Season 22
Tourneys
[Megathread] Daily Proleagues [BSL22] Open Qualifiers & Ladder Tours Small VOD Thread 2.0 IPSL Spring 2026 is here!
Strategy
Simple Questions, Simple Answers Soma's 9 hatch build from ASL Game 2 Fighting Spirit mining rates
Other Games
General Games
Stormgate/Frost Giant Megathread General RTS Discussion Thread Nintendo Switch Thread Path of Exile Dawn of War IV
Dota 2
Official 'what is Dota anymore' discussion The Story of Wings Gaming
League of Legends
G2 just beat GenG in First stand
Heroes of the Storm
Simple Questions, Simple Answers Heroes of the Storm 2.0
Hearthstone
Deck construction bug Heroes of StarCraft mini-set
TL Mafia
Five o'clock TL Mafia Mafia Game Mode Feedback/Ideas Vanilla Mini Mafia TL Mafia Community Thread
Community
General
US Politics Mega-thread Things Aren’t Peaceful in Palestine Canadian Politics Mega-thread Russo-Ukrainian War Thread Mexico's Drug War
Fan Clubs
The IdrA Fan Club
Media & Entertainment
Movie Discussion! [Req][Books] Good Fantasy/SciFi books [Manga] One Piece
Sports
Formula 1 Discussion 2024 - 2026 Football Thread Tokyo Olympics 2021 Thread General nutrition recommendations Cricket [SPORT]
World Cup 2022
Tech Support
Laptop capable of using Photoshop Lightroom?
TL Community
The Automated Ban List
Blogs
Funny Nicknames
LUCKY_NOOB
Money Laundering In Video Ga…
TrAiDoS
Iranian anarchists: organize…
XenOsky
FS++
Kraekkling
Shocked by a laser…
Spydermine0240
Unintentional protectionism…
Uldridge
ASL S21 English Commentary…
namkraft
Customize Sidebar...

Website Feedback

Closed Threads



Active: 4074 users

really interesting puzzle, took me a while!

Blogs > DoctorHelvetica
Post a Reply
Normal
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
England2669 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
cascades
Profile Blog Joined October 2009
Singapore6122 Posts
October 31 2009 17:55 GMT
#21
It is just that in a real life situation your chances of getting 3 perfectly logical person is one in 6 billion.
HS: cascades#1595 || LoL: stoppin
DoctorHelvetica
Profile Blog Joined July 2008
United States15034 Posts
October 31 2009 18:15 GMT
#22
How stupid would you have to be to see two white hats and not immediately call out black. It requires D to not be blind, not to be intelligent.
RIP Aaliyah
Zinbiel
Profile Joined October 2008
Sweden878 Posts
October 31 2009 18:22 GMT
#23
On November 01 2009 03:15 DoctorHelvetica wrote:
How stupid would you have to be to see two white hats and not immediately call out black. It requires D to not be blind, not to be intelligent.

agreed, you would actually have to be criminally stupid not to see the connection "2 whites and 2 black total, I see 2 white I have black". Sure there are lots of that kind of people in the world but no more than 48.3% I'd say. Btw anyone else who came up with the same solution as I did to madnessman's puzzle? Is there another way?
Backho fan since 080416. Favourite terran: Mind. Favourite Zerg: Jaedong.
Leath
Profile Blog Joined July 2006
Canada1724 Posts
October 31 2009 18:52 GMT
#24
I think I may have found the solution:


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.
http://www.kongregate.com/?referrer=Sagess
Musoeun
Profile Blog Joined March 2009
United States4324 Posts
November 01 2009 01:55 GMT
#25
This was a weird one. I ran through the possibilities, and I guess "intuited" the correct answer from that but couldn't figure out *why* it was right for the longest time. I'm not sure if this makes me smart or stupid.
Don't Shoot the Penguins. | Dance, 성은, dance! | Killer FanKlub | Action sucks. | Storm Terran hwaiting.
WhiteNights
Profile Blog Joined October 2009
United States252 Posts
November 01 2009 01:58 GMT
#26
guess: everybody knows D sees white and black because otherwise he would call

but C sees white so he knows he has black

check: i win

hooray
May your sky be always clear, may your smile be always bright, and may you be forever blessed for that moment of happiness which you gave to another lonely and grateful heart!
N.geNuity
Profile Blog Joined July 2009
United States5112 Posts
November 01 2009 02:03 GMT
#27
Good thing C knows there is a dude behind him! If they can't communicate, how could he know?
iu, seungah, yura, taeyeon, hyosung, lizzy, suji, sojin, jia, ji eun, eunji, soya, younha, jiyeon, fiestar, sinb, jung myung hoon godtier. BW FOREVERR
comabreaded
Profile Blog Joined July 2003
United States2166 Posts
November 23 2009 18:35 GMT
#28
the picture made it rly ez
I put the fu in fun
DivinO
Profile Blog Joined July 2009
United States4796 Posts
November 23 2009 18:39 GMT
#29
Actually got this one. :D In not too long.
LiquipediaBrain in my filth.
EtherealDeath
Profile Blog Joined July 2007
United States8366 Posts
November 23 2009 19:19 GMT
#30
Heh I read this problem initially as why does A know his color, and spent a few minutes wondering how it was possible that + Show Spoiler +
C could not know his color. Then I realized I misread the problem and in fact the answer was C XD
Athos
Profile Blog Joined February 2008
United States2484 Posts
November 23 2009 19:40 GMT
#31
This one completely baffled me mainly because I underestimated there intelligence.
haster27
Profile Blog Joined October 2009
Taiwan809 Posts
November 23 2009 19:41 GMT
#32
C. Easy.
Normal
Please log in or register to reply.
Live Events Refresh
The PiG Daily
22:00
Best Games of SC
Solar vs ByuN
MaxPax vs Solar
Rogue vs Percival
Cure vs Solar
herO vs Solar
LiquipediaDiscussion
[ Submit Event ]
Live Streams
Refresh
StarCraft 2
RuFF_SC2 293
NeuroSwarm 275
Nina 155
ProTech121
StarCraft: Brood War
Shuttle 622
Noble 81
Icarus 4
Dota 2
monkeys_forever765
LuMiX1
League of Legends
JimRising 610
Heroes of the Storm
Khaldor133
Other Games
ViBE121
Trikslyr78
Mew2King68
Organizations
Other Games
gamesdonequick867
Dota 2
PGL Dota 2 - Main Stream125
StarCraft 2
Blizzard YouTube
StarCraft: Brood War
BSLTrovo
sctven
[ Show 13 non-featured ]
StarCraft 2
• davetesta53
• AfreecaTV YouTube
• intothetv
• Kozan
• IndyKCrew
• LaughNgamezSOOP
• Migwel
• sooper7s
StarCraft: Brood War
• BSLYoutube
• STPLYoutube
• ZZZeroYoutube
League of Legends
• Doublelift5173
• Lourlo633
Upcoming Events
RSL Revival
6h 55m
herO vs MaxPax
Rogue vs TriGGeR
BSL
16h 55m
Replay Cast
20h 55m
Replay Cast
1d 5h
Afreeca Starleague
1d 6h
Sharp vs Scan
Rain vs Mong
Wardi Open
1d 8h
Monday Night Weeklies
1d 13h
Sparkling Tuna Cup
2 days
Afreeca Starleague
2 days
Soulkey vs Ample
JyJ vs sSak
Replay Cast
3 days
[ Show More ]
Afreeca Starleague
3 days
hero vs YSC
Larva vs Shine
Kung Fu Cup
3 days
Replay Cast
3 days
KCM Race Survival
4 days
The PondCast
4 days
WardiTV Team League
4 days
Replay Cast
4 days
WardiTV Team League
5 days
RSL Revival
6 days
Cure vs Zoun
WardiTV Team League
6 days
BSL
6 days
Liquipedia Results

Completed

Jeongseon Sooper Cup
WardiTV Winter 2026
Underdog Cup #3

Ongoing

KCM Race Survival 2026 Season 1
BSL Season 22
CSL Elite League 2026
RSL Revival: Season 4
Nations Cup 2026
NationLESS Cup
BLAST Open Spring 2026
ESL Pro League S23 Finals
ESL Pro League S23 Stage 1&2
PGL Cluj-Napoca 2026
IEM Kraków 2026
BLAST Bounty Winter 2026
BLAST Bounty Winter Qual

Upcoming

ASL Season 21
Acropolis #4 - TS6
2026 Changsha Offline CUP
CSL 2026 SPRING (S20)
CSL Season 20: Qualifier 1
Acropolis #4
IPSL Spring 2026
Kung Fu Cup 2026 Grand Finals
HSC XXIX
uThermal 2v2 2026 Main Event
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
CCT Season 3 Global Finals
IEM Rio 2026
PGL Bucharest 2026
Stake Ranked Episode 1
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.