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Re: Variable number of foreach loops (non-recursive solution)by smls (Friar) |
on Nov 28, 2013 at 17:44 UTC ( [id://1064853]=note: print w/replies, xml ) | Need Help?? |
Non-recursive solutionFor completeness, here's a solution that does not use a recursive subroutine:
The "Determine the next set of indices" step may seem a little complicated at first sight, but it becomes more intuitive if you think of the @indices array as an integer number (with each element representing a digit), and imagine that we want to "increment" that "number" by 1. It's not a decimal (i.e. base-10) number, but rather one where each digit can have a different base (i.e. the sizes of the input arrays) - but that doesn't really change anything. Incrementing the "number" by 1 works just like the integer addition (here with an addend of 1) that you were taught back in primary school: Start with the right-most digit; increment it; if it's still within the valid range of digits then you're done; if instead it went above the limit then wrap it around to zero, "carry the one", and repeat the same steps with the next digit to the left. Update: Performance comparisonInterestingly, my iterative solution seems to be significantly slower than BrowserUK's recursive solution, at least when running on my PC and with various different numbers/sizes of input arrays I tried:
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