c*********s
发帖数: 327 | 1 Five non-same-sex couples, including the host and his wife, attend a party.
Throughout the evening, as introductions are made, various partygoers shake
hands. However, couples that are together do not shake hands with each other
. At the end of the evening, the host asks the nine other attendees how many
hands they shook and obtains nine different answers. How many hands did the
host shake and how many hands did his wife shake?
现在知道那九个数是（0－8）， No0 and N8 is a couple.
剩下(1,7), (2,6), (3,5) 是对对， 但 | C*********r
发帖数: 8 | 2
.
shake
other
many
the
interesting problem
I believe (8 0) (7 1) (6 2) (3 5) are couples
that leaves 4, which should be the host's wife, and which leaves the host no
choice but 4
【在 c*********s 的大作中提到】
: Five non-same-sex couples, including the host and his wife, attend a party.
: Throughout the evening, as introductions are made, various partygoers shake
: hands. However, couples that are together do not shake hands with each other
: . At the end of the evening, the host asks the nine other attendees how many
: hands they shook and obtains nine different answers. How many hands did the
: host shake and how many hands did his wife shake?
: 现在知道那九个数是（0－8）， No0 and N8 is a couple.
: 剩下(1,7), (2,6), (3,5) 是对对， 但
| J*******g
发帖数: 267 | 3 1. (0, 8) is a couple, draw a diagram to represent all the handshakes of
this couple
2. argue that (1, 7) is a couple (similar argument as the argument for (0, 8
), just remember that each person other than 0 and 8 already has one
handshake, particularly with 8).
3. continue this process, and find out that (2, 6) is a couple and (3, 5) is
a couple, leaving 4 as a singleton, which must be the host's wife, hence
the host must also have 4 handshakes
.
shake
other
many
the
【在 c*********s 的大作中提到】
: Five non-same-sex couples, including the host and his wife, attend a party.
: Throughout the evening, as introductions are made, various partygoers shake
: hands. However, couples that are together do not shake hands with each other
: . At the end of the evening, the host asks the nine other attendees how many
: hands they shook and obtains nine different answers. How many hands did the
: host shake and how many hands did his wife shake?
: 现在知道那九个数是（0－8）， No0 and N8 is a couple.
: 剩下(1,7), (2,6), (3,5) 是对对， 但
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