• Log InLog In
  • Register
Liquid`
Team Liquid Liquipedia
EDT 22:14
CEST 04:14
KST 11:14
  • 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 - The Finalists14[ASL21] Ro16 Preview Pt1: Fresh Flow9[ASL21] Ro24 Preview Pt2: News Flash10[ASL21] Ro24 Preview Pt1: New Chaos0Team Liquid Map Contest #22 - Presented by Monster Energy21
Community News
2026 GSL Season 1 Qualifiers11Maestros of the Game 2 announced32026 GSL Tour plans announced13Weekly Cups (April 6-12): herO doubles, "Villains" prevail1MaNa leaves Team Liquid22
StarCraft 2
General
Blizzard Classic Cup @ BlizzCon 2026 - $100k prize pool 2026 GSL Tour plans announced MaNa leaves Team Liquid Team Liquid Map Contest #22 - The Finalists Weekly Cups (April 6-12): herO doubles, "Villains" prevail
Tourneys
Sparkling Tuna Cup - Weekly Open Tournament GSL CK: More events planned pending crowdfunding 2026 GSL Season 1 Qualifiers Master Swan Open (Global Bronze-Master 2) SEL Doubles (SC Evo Bimonthly)
Strategy
Custom Maps
[D]RTS in all its shapes and glory <3 [A] Nemrods 1/4 players [M] (2) Frigid Storage
External Content
Mutation # 522 Flip My Base The PondCast: SC2 News & Results Mutation # 521 Memorable Boss Mutation # 520 Moving Fees
Brood War
General
[ASL21] Ro16 Preview Pt2: All Star Data needed RepMastered™: replay sharing and analyzer site Gypsy to Korea ASL21 General Discussion
Tourneys
[Megathread] Daily Proleagues Escore Tournament StarCraft Season 2 [ASL21] Ro16 Group A [ASL21] Ro16 Group B
Strategy
Simple Questions, Simple Answers What's the deal with APM & what's its true value Any training maps people recommend? Fighting Spirit mining rates
Other Games
General Games
Nintendo Switch Thread General RTS Discussion Thread Battle Aces/David Kim RTS Megathread Stormgate/Frost Giant Megathread Starcraft Tabletop Miniature Game
Dota 2
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
Vanilla Mini Mafia Mafia Game Mode Feedback/Ideas TL Mafia Community Thread Five o'clock TL Mafia
Community
General
Things Aren’t Peaceful in Palestine US Politics Mega-thread Russo-Ukrainian War Thread YouTube Thread Canadian Politics Mega-thread
Fan Clubs
The IdrA Fan Club
Media & Entertainment
[Manga] One Piece Anime Discussion Thread [Req][Books] Good Fantasy/SciFi books Movie Discussion!
Sports
2024 - 2026 Football Thread McBoner: A hockey love story Formula 1 Discussion Cricket [SPORT]
World Cup 2022
Tech Support
[G] How to Block Livestream Ads
TL Community
The Automated Ban List
Blogs
Reappraising The Situation T…
TrAiDoS
lurker extra damage testi…
StaticNine
Broowar part 2
qwaykee
Funny Nicknames
LUCKY_NOOB
Iranian anarchists: organize…
XenOsky
ASL S21 English Commentary…
namkraft
Customize Sidebar...

Website Feedback

Closed Threads



Active: 2269 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
England2670 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
Replay Cast
00:00
Code For Giants Cup #29
Liquipedia
BSL
19:00
RO32 Group D
StRyKeR vs rasowy
Artosis vs Aether
JDConan vs OyAji
Hawk vs izu
LiquipediaDiscussion
[ Submit Event ]
Live Streams
Refresh
StarCraft 2
RuFF_SC2 225
ProTech148
StarCraft: Brood War
GuemChi 6250
Mind 123
ggaemo 66
Dota 2
monkeys_forever812
NeuroSwarm135
League of Legends
JimRising 770
Super Smash Bros
hungrybox704
Heroes of the Storm
Khaldor150
Other Games
summit1g15925
tarik_tv10068
Artosis780
C9.Mang0412
Maynarde161
ViBE133
WinterStarcraft91
Mew2King34
Organizations
Other Games
gamesdonequick622
BasetradeTV317
StarCraft 2
Blizzard YouTube
StarCraft: Brood War
BSLTrovo
sctven
[ Show 13 non-featured ]
StarCraft 2
• Hupsaiya 112
• Mapu5
• AfreecaTV YouTube
• intothetv
• Kozan
• IndyKCrew
• LaughNgamezSOOP
• Migwel
• sooper7s
StarCraft: Brood War
• BSLYoutube
• STPLYoutube
• ZZZeroYoutube
Other Games
• Scarra1157
Upcoming Events
Replay Cast
6h 46m
Wardi Open
7h 46m
Afreeca Starleague
7h 46m
Bisu vs Ample
Jaedong vs Flash
Monday Night Weeklies
13h 46m
RSL Revival
23h 46m
GSL
1d 5h
Afreeca Starleague
1d 7h
Barracks vs Leta
Royal vs Light
WardiTV Map Contest Tou…
1d 8h
RSL Revival
2 days
Replay Cast
2 days
[ Show More ]
The PondCast
3 days
KCM Race Survival
3 days
WardiTV Map Contest Tou…
3 days
CranKy Ducklings
3 days
Escore
4 days
RSL Revival
4 days
WardiTV Map Contest Tou…
5 days
Universe Titan Cup
5 days
Rogue vs Percival
Ladder Legends
5 days
uThermal 2v2 Circuit
5 days
BSL
5 days
Sparkling Tuna Cup
6 days
WardiTV Map Contest Tou…
6 days
Ladder Legends
6 days
BSL
6 days
Replay Cast
6 days
Liquipedia Results

Completed

Escore Tournament S2: W3
RSL Revival: Season 4
NationLESS Cup

Ongoing

BSL Season 22
ASL Season 21
CSL 2026 SPRING (S20)
IPSL Spring 2026
KCM Race Survival 2026 Season 2
StarCraft2 Community Team League 2026 Spring
WardiTV TLMC #16
Nations Cup 2026
IEM Rio 2026
PGL Bucharest 2026
Stake Ranked Episode 1
BLAST Open Spring 2026
ESL Pro League S23 Finals
ESL Pro League S23 Stage 1&2
PGL Cluj-Napoca 2026
IEM Kraków 2026

Upcoming

Escore Tournament S2: W4
Acropolis #4
BSL 22 Non-Korean Championship
CSLAN 4
Kung Fu Cup 2026 Grand Finals
HSC XXIX
uThermal 2v2 2026 Main Event
2026 GSL S2
RSL Revival: Season 5
2026 GSL S1
XSE Pro League 2026
IEM Cologne Major 2026
Stake Ranked Episode 2
CS Asia Championships 2026
IEM Atlanta 2026
Asian Champions League 2026
PGL Astana 2026
BLAST Rivals Spring 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.