| Title: | Mathematics at DEC |
| Moderator: | RUSURE::EDP |
| Created: | Mon Feb 03 1986 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2083 |
| Total number of notes: | 14613 |
Scene: the African jungle 3 missionaries and 3 natives want to get to the other side of a wide river. They have a boat with them which will take up to 2 people. There is a constraint however. The natives do not wish to be converted, which will happen if they are outnumbered anywhere by missionaries. So you can't have 2 natives left alone with 3 missionaries, or 1 native left alone with either 2 or 3 missionaries. Only one of the missionaries and one of the natives know how to row the boat. How do you get them all across the river? Regards, Andrew.
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 1786.1 | might be easier just to get converted ;) | STAR::ABBASI | i like to sleep | Wed Sep 08 1993 16:05 | 33 |
.1
easy, let M stand for missionaries, N for native.
let M* be the M who can row, let N* be the N who can row.
0. side1: N1,N2,N*,M1,M2,M* side2: empty
1. M1,M* cross the river, M* brings back the boat.
side1: N1,N2,N*,M2,M* side2: M1
2. M2,M* cross the river, M* brings back the boat.
side1: N1,N2,N*,M* side2: M1,M2
3. N1,M* corss the river, M1,M* bring back the boat.
side1: N2,N*,M1,M* side2: M2,N1
4. N*,M* corss the river, N*,M2 bring back the boat.
side1: N2,N*,M1,M2 side2 : M*,N1
5. N*,N2 cross the river, M* bring back the boat
side1: M1,M*,M* side2: N*,N1,N2,
6. M*,M1 corss the river, N* bring back the boat
side1: M2,N* side2:M*,M1,N1,N2
7. N*,M1 corss the river.
side1: empty side2: N1,N2,N*,M1,M2,M*
\nasser
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| 1786.2 | not quite | HERON::BUCHANAN | The was not found. | Thu Sep 09 1993 05:35 | 21 |
> easy, let M stand for missionaries, N for native. > let M* be the M who can row, let N* be the N who can row. > > 0. side1: N1,N2,N*,M1,M2,M* side2: empty > > 1. M1,M* cross the river, M* brings back the boat. > side1: N1,N2,N*,M2,M* side2: M1 > > 2. M2,M* cross the river, M* brings back the boat. > side1: N1,N2,N*,M* side2: M1,M2 No problems so far. > 3. N1,M* corss the river, Uh-oh! As the boat lands, N1 finds himself surrounded by 3 missionaries, who start singing at him. Try again. Andrew. | |||||
| 1786.3 | i assumed this was ok to assume | STAR::ABBASI | i like to sleep | Thu Sep 09 1993 11:35 | 16 |
.-1
but i assumed that they need more time to get converted than the
time avaliable to switch seats on the boat when the boat gets to the
other side?
i mean when an N gets to the other side, the other M's wont stay
with him on that side of the shore for long becuase one of the M's
will RIGHT AWAY jump to the boat and head back to the other side!
like, these missionaries must be real good to be able to convert
a native this fast while they are boarding the boat !
....ok..i'll think more of this, but it look harder now :(
\nasser
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| 1786.4 | KDX200::ROBR | Orange squares suck. | Thu Sep 09 1993 20:55 | 25 | |
heres a messy solution (to make up for the wonderful gambling
discussion :') )
abc = natives (a is sailor)
123 = missionaries (1 is sailor)
left bank transit right bank
------------------------------------------------------------
abc 123
bc 13 a2 -> a 2
abc 13 <- a 2
abc 13 -> 123
abc 1 <- 1 23
c 1 ab -> ab 23
ac 12 <- a2 b 3
c 2 a1 -> ab 13
ac 23 <- a3 b1
23 ac -> abc1
123 <- 1 abc
3 12 -> abc 12
13 <- 1 abc 2
13 -> abc 123
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