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Does anyone provide some hints about this problem?
I can't figure out the recurrence equation either in O(n^4) or O(n^3).
Any comment or example will help me a lot.
Thanks.

Could anyone provide some hints about this problem?
As far as I know, this problem can be solved by max-flow algorithm,
but I can't figure out how to map the problem to the corresponding graph.
I think any explanation or example will help.

Thanks in advance.