656 - Optimal Programs

[Jer]

Can anyone explain the problem to me?

I don't know why the first test data is like that...

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4
1 2 3 4
0 -2 -6 -12

Program 1
DUP DUP MUL SUB

Thanks for your help

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[Observer]

OK. When the input is 1,

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1          <- Initially

1 1 1      <- After two DUPs

1 1        <- Multiply the top 2 entries

0          <- Subtraction of the 2 entries

Or when the input is 2,

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2          <- Initially

2 2 2      <- After two DUPs

2 4        <- Multiply the top 2 entries

-2         <- Subtraction of the 2 entries

I'm sure you know what's going on for input = 3 or 4

Hope it helps~