River IQ Test

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The River IQ Test (aka River IQ Game) is a mental puzzle. The name originates as it supposedly is given as an IQ test to job applicants in China. The puzzle is in Chinese, but can be completed with ease once the rules have been translated.

Screen shot at the start of the puzzle. The game characters and river are clearly shown.

1 The aim
2 The rules
3 Solution
4 Application to solve the problem
5 See also
6 External links

[edit] The aim

The object is to get everyone (father, two sons, mother, two daughters, police officer and thief) from one side of the river to the other whilst adhering to certain rules.

[edit] The rules

The following rules apply:

At most two persons on the raft at any time
The father cannot stay with any of the daughters without their mother's presence
The mother cannot stay with any of the sons without their father's presence
The thief (striped shirt) cannot stay with any family member if the police officer is not there
Only the father, the mother and the police officer know how to operate the raft

[edit] Solution

Initially the puzzle seems daunting with a large number of possible moves, however there is in fact very little choice as the wrong moves prevent any further moves. There are only two possible sequences of moves that will accomplish the goal in the least number of steps.

Move No.	Across	Back
1	Police Officer, Thief	Police Officer
2	Police Officer, Son 1	Police Officer, Thief
3	Father, Son 2	Father
4	Father, Mother	Mother
5	Police Officer, Thief	Father
6	Father, Mother	Mother
7	Mother, Daughter 1	Police Officer, Thief
8	Police Officer, Daughter 2	Police Officer
9	Police Officer, Thief

Move No.	Across	Back
1	Police Officer, Thief	Police Officer
2	Police Officer, Daughter 1	Police Officer, Thief
3	Mother, Daughter 2	Mother
4	Father, Mother	Father
5	Police Officer, Thief	Mother
6	Father, Mother	Father
7	Father, Son 1	Police Officer, Thief
8	Police Officer, Son 2	Police Officer
9	Police Officer, Thief