Help me figure out this logic problem, it seems impossible~!

Cuda1447

Lifer
Jul 26, 2002
11,757
0
71
Ok a basic run down of the problem.


You've got 5 people, they have to go across this bridge in 30 seconds. They need to go in ones or twos. They have to carry a lamp with them at all times when crossing the bridge. They must cross at the slowest one in the groups speed. They cross at these speeds

1 second
3 seconds
6 seconds
8 seconds
12 seconds


So logic would make you think have the 1 second guy go across with everyone and come back as fast as he could. But that doesn't work.
 

GoingUp

Lifer
Jul 31, 2002
16,720
1
71
Originally posted by: Cuda1447
Ok a basic run down of the problem.


You've got 5 people, they have to go across this bridge in 30 seconds. They need to go in ones or twos. They have to carry a lamp with them at all times when crossing the bridge. They must cross at the slowest one in the groups speed. They cross at these speeds

1 second
3 seconds
6 seconds
8 seconds
12 seconds


So logic would make you think have the 1 second guy go across with everyone and come back as fast as he could. But that doesn't work.


yea thats what I tried too....
 

Basilisk6

Member
Jan 25, 2001
137
0
76
Hint: The trick to any bridge crossing problems like this is that you need to get the slowest people to go across together, effectively removing the second slowest person from the equation. I'll let you try it with that hint.
 

Cuda1447

Lifer
Jul 26, 2002
11,757
0
71
Originally posted by: Basilisk6
Hint: The trick to any bridge crossing problems like this is that you need to get the slowest people to go across together, effectively removing the second slowest person from the equation. I'll let you try it with that hint.

still doesn't work! Just gimme the solution if your so smart lol
 

lozina

Lifer
Sep 10, 2001
11,709
8
81
I've seen many of these type of problems. The trick is to take the two fastest guys across, one comes back with lamp. then the two slowest guys go accross, and the other fastest guy bring the lamp back. that move saves alot of time.
 

GoingUp

Lifer
Jul 31, 2002
16,720
1
71
Originally posted by: Basilisk6
Hint: The trick to any bridge crossing problems like this is that you need to get the slowest people to go across together, effectively removing the second slowest person from the equation. I'll let you try it with that hint.

doesnt work
 

theApp

Member
Dec 1, 2001
139
0
0
Spoiler:

























First, send the 1 and 3 across. Send the 1 back. Send the 1 and the 6 across. Send the 1 back. Send the 12 and 8 across, and send the 3 back. Finally send the 3 and 1 across. Done in 29 seconds.

3 + 1 + 6 + 1 + 12 + 3 + 3 = 29
 

Basilisk6

Member
Jan 25, 2001
137
0
76
Originally posted by: Gobadgrs
Originally posted by: Basilisk6
Hint: The trick to any bridge crossing problems like this is that you need to get the slowest people to go across together, effectively removing the second slowest person from the equation. I'll let you try it with that hint.

doesnt work

Sure it does. Solution:














Send 1 and 3 (3 seconds)
Send 1 (4 seconds)
*Send 8 and 12 (16 seconds)*
Send 3 (19 seconds)
Send 1 and 6 (25 seconds)
Send 1 (26 seconds)
Send 1 and 3 (29 seconds)

And you're done with 1 second to spare.
 

Cuda1447

Lifer
Jul 26, 2002
11,757
0
71
Originally posted by: lozina
I've seen many of these type of problems. The trick is to take the two fastest guys across, one comes back with lamp. then the two slowest guys go accross, and the other fastest guy bring the lamp back. that move saves alot of time.

Ahh ok, I figured it out now. lol
 

Emveach

Senior member
Feb 3, 2003
319
0
0
****SPOLIER*****


























1) 1 and 3, send 1 back
2) 8 and 12, send 3 back
3)6 and 1, send 1 baclk
4)1 and 3.

Finish with 29 seconds.
 

GoingUp

Lifer
Jul 31, 2002
16,720
1
71
got it!

send over 1 and 3, then send back 1, send over 8 and 12 then send back 3 send over 1 and 5 then send back 1 then send 1 and 3