37 replies to this topic

[rookie1ja]

Humans and Monkeys - Back to the River Crossing Puzzles
Three humans, one big monkey and two small monkeys are to cross a river:
* Only humans and the big monkey can row the boat.
* At all times, the number of humans on either side of the river must be greater or equal to the number of monkeys on that side. (Or else the humans will be eaten by the monkeys!)
* The boat only has room for 2 (monkeys or humans).
* Monkeys can jump out of the boat when it's banked.

This old topic is locked since it was answered many times. You can check solution in the Spoiler below.
Pls visit New Puzzles section to see always fresh brain teasers.

Spoiler for Solution

Humans and Monkeys - solution
The three columns represent the left bank, the boat, and the right bank respectively. The < or > indicates the direction of motion of the boat.
HHHMmm . .
HHHm Mm> .
HHHm <M m
HHH Mm> m
HHH <M mm
HM HH> mm
HM <Hm Hm
Hm HM> Hm
Hm <Hm HM
mm HH> HM
mm <M HHH
m Mm> HHH
m <M HHHm
. Mm> HHHm
. . HHHMmm

[mr_pitcher_44]

HUH!?!?

[mr_pitcher_44]

HUH!?!? in english please!

[rookie1ja]

HUH!?!? in english please!

. is an empty bank (or an empty boat in the first and the last step)
H is a human
M is a big monkey
m is a small monkey
> is going right
< is going left

[onyx_sisco]

ok, nevermind, I didn't understand the monkeys jump out when it banks at first....

[dak1530]

ADMIN this is yours 15 steps (and this is mine 12 steps)

The three columns represent the left bank,
the boat, and the right bank respectively.
The < or > indicates the direction of motion of the boat.
HHHMmm . . (HHHMmm . .)
HHHm Mm> . (HHHm Mm> .)
HHHm HHH Mm> m (HHH Mm> m)
HHH HM HH> mm (HM HH> mm)
HM Hm HM> Hm ---------
Hm Hm)
mm HH> HM (Mm mm HHm)
m Mm> HHH (M m HHHMmm)
. Mm> HHHm
. . HHHMmm

[imtcb]

ADMIN this is yours 15 steps (and this is mine 12 steps)

The three columns represent the left bank,
the boat, and the right bank respectively.
The < or > indicates the direction of motion of the boat.
HHHMmm . . (HHHMmm . .)
HHHm Mm> . (HHHm Mm> .)
HHHm HHH Mm> m (HHH Mm> m)
HHH HM HH> mm (HM HH> mm)
HM Hm HM> Hm ---------
Hm Hm)
mm HH> HM (Mm <- This step would result in an eaten human when he arrived at the other side! 1 human, 2 monkeys.
mm HHm)
m Mm> HHH (M m HHHMmm)
. Mm> HHHm
. . HHHMmm

[kingmadmushroom]

if the number of humans is zero on one side but there are multiple monkeys does it matter? (after all, the humans cannot be eaten if they are not there)

[Ankur]

how about this:-

HHHMmm...
HHMm >Hm...
HHMm...Hm
HM >Hm...Hm
HM...HHmm
>HM...HHmm
...HHHMmm

sounds rite ???

[coolkid101]

HHH, Mmm
HH mm HM> ........
HH mm <M H
HH m Mm> H
HH m <H Mm
HH Hm> Mm
HH <H Mmm
H HH> Mmm
H <M HH mm
........ HM> HHH Mmm
........ ...... HHH Mmm

Isn't this right