Here a test the Japanese use for hiring employees in the IT sector. (At least that is what it says)
Click on the round button
You see a family of six, (Mother, Father, two boys, two girls) and a policeman and a prisoner. The goal is to get everyone seen here across the river following these rules:
1. Maximum of two people can go on the float.
2. Father cannot be with any of his daughters without the mother being present.
3. Mother cannot be with any of her sons without the father being present.
4. The prisoner can not be in the presence of family members without the policeman.
5. Only the policeman and parents can drive the float.
Go ahead and give it a try. The average person is supposed to be able to do it in about 15 minutes.
If you figured out how to do it, you can share it below.� Correct answers will be moved to the Solutions Page�to keep it challenging here.� You can check them out,�but try to do it on your own.
-DJ Allyn
November 29th, 2007 at 9:57 pm
I will give you the first move hint:
The policeman and the prisoner go over first
December 8th, 2007 at 12:34 pm
How long did it take you?
January 2nd, 2008 at 1:24 am
1. Cop and Son 1 cross ——-> Son 1
2. Cop comes back
3. Cop and Son 2 cross ——-> Sons 1,2
4. Cop comes back
5. Cop and Daughter 1 cross ——-> Sons 1,2, Daughter 1
6. Cop comes back
7. Cop and Daughter 2 cross ——-> Sons 1,2 , Daughters 1,2
8. Cop comes back
9. Cop and Prisoner cross ——-> Sons 1,2 , Daughters 1,2 and Prisoner
10. Cop comes back
11. Cop and Father cross ——-> Sons 1,2, Daughters 1,2 , Prisoner and Cop
12. Father comes back
13. Father and Mother cross ——-> Sons 1,2, Daughters 1,2 , Prisoner, Cop, Father and Mother
Wrong
January 31st, 2008 at 8:51 pm
the cop handles the float for all crossings
the cop always returns across the river alone
1. cop takes Boy 1 across B1 |~~\C/~~| M F B2 D1 D2 P
2. cop takes boy 2 across B1 B2 |~~\C/~~| M F D1 D2 P
3. cop takes father across B1 B2 F |~~\C/~~| M D1 D2 P
4. cop takes prisoner across B1 B2 F P |~~\C/~~| M D1 D2
5. cop takes mom across B1 B2 F P M |~~\C/~~| D1 D2
6. cop takes daughter 1 across B1 B2 F P M D1 |~~\C/~~| D2
7. cop takes daughter 2 across B1 B2 F P M D1 D2 C |~~ ~~|
no return necessary as all are across the river
total, counting the 6 solitary return crossings by the cop, 13
otpu
Wrong
February 5th, 2008 at 8:18 am
Obviously the only person who completed this thing is the second entry. ahriman and otpu say that the cop takes everybody across. That leaves the prisoner alone with the family members, and if you even tried that once, you’d know it doesn’t work. Good job Dawn. This works. It can be changed up very slightly, but it is the guideline to getting everyone across.
March 24th, 2008 at 8:41 am
Just saw this link, it is similar to a problem posed in Russian culture. Anyhow Dawns response works but there is another solution. Her step of transporting the prisoner first is unnecessary. This also makes the second step unnecessary and the fourth modified to only the cop. So just start with transporting the boy, or maybe the “women first” it will work that way also. Then at the end a step can be eliminated. At her 14 why not just send mom and dad back. Dad stays and mom picks up last girl. Then mom returns to pick up dad. It will then be completed in 14 steps instead of 17.
April 2nd, 2008 at 1:12 pm
Rule # 4 is incorrect, It should read: The prisoner can not be in the presence of family members without the policeman.
April 3rd, 2008 at 9:12 am
No, the prisoner and the policeman can be separated if two or more members of the family are present.
April 11th, 2008 at 9:44 am
Rule #4 IS incorrect. dean is right, DJ Allyn is wrong. Try it, you’ll see that if the prisoner is with any number of family members without the policeman present, she punches them.
April 11th, 2008 at 4:22 pm
You are correct. I changed it to reflect that.
I didn’t write the instructions, it must have been something in the translation. I didn’t pay that close of attention to it since I already knew the solution to the puzzle.
I have also moved the correct solution(s) to another page so that it is more challenging to the hundreds of people who come here every day to try their hand at the puzzle.
April 15th, 2008 at 12:43 pm
Cop and prisoner across
Cop back
Cop and son 1 across
Cop and prisoner back
Father and Son 2 across
Father back
Mother and Father across
Mother back
Mother and daughter 1 across
Mother and father back
Mother and daughter 2 across
Mother back
Mother and father across
Mother or father back
Mother or father and cop across
cop back
cop and prisoner across
Wrong
(Try it — it won’t work)
May 14th, 2008 at 12:49 pm
what was dawns answer i dont see it in the thread