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| -rw-r--r-- | challenge-111/james-smith/README.md | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/challenge-111/james-smith/README.md b/challenge-111/james-smith/README.md index f9388bea6e..96436232a7 100644 --- a/challenge-111/james-smith/README.md +++ b/challenge-111/james-smith/README.md @@ -244,7 +244,7 @@ cmpthese(100_000, { }); ``` -## Addendum - using hash keys +## Addendum 1 - using hash keys As some people have used hash slices to solve this problem - I thought I would look into this to -- Colin thought this would help in the perl @@ -266,7 +266,7 @@ Looking at performance - this is approximately 53% slower than the search algorithm, and therefore less than a tenth of the speed of the optimal solution. -## Addendum - passing an array rather than an arrayref +## Addendum 2 - passing an array rather than an arrayref I quickly checked to see if by passing the matrix as an array rather than an arrayref was any faster - one less derefernce - but it is not - it @@ -286,6 +286,42 @@ the same speed or slightly slower. | DNF | 20,080/s | 887% | 308% | 277% | 177% | *156%* | *140%* | -- | -13% | | Optimal | 23,095/s | 1,035% | 370% | 333% | 218% | *194%* | *176%* | 15% | -- | +## Addendum 3 - caching "flattening" + +Optimizations like these are great if you are in the middle of a tight loop and calling the function a number +of times - if this is the same matrix each time - we may get some performance boosts by pre-flattening the matrix. + +I've included two more functions "Grep-@" & "Hash-%" which replicate "Grep-Map" and "Hash" to show how this can +speed things up.. The compute on the fly hash is the slowest method - but pre-cacheing the hash is 30 times faster, +the pre-flattened array speeds up the grep - but only by a factor of 2 and so is still only half the speed of +the *do not flatten* versions. + +**Note:** The second parameter in each of these is the respective flattened arrayref or hashref. + +```perl +sub find_val_grep_pre { + my($v,$m)=@_; + return 0 + grep { $_ == $v } @{$m}; +} + +sub find_val_hash_pre { + return exists $_[1]{$_[0]} ? 1: 0; +} +``` + +| Method | Rate | Hash | Search | GrepMap | MapGrep | *Flat* | *Flat@* | **Grep@** | DNF | Opt | **Hash%** | +| ----------- | --------: | ------: | ------: | -------: | -------: | --------: | ----------: | ---------: | -----: | ------: | ----------: | +| Hash | 1,932/s | -- | -60% | -64% | -73% | *-77%* | *-77%* | **-82%** |-90% | -92% | **-97%** | +| Search | 4,824/s | 150% | -- | -10% | -33% | *-42%* | *-43%* | **-55%** |-76% | -79% | **-92%** | +| Grep-Map | 5,388/s | 179% | 12% | -- | -25% | *-36%* | *-36%* | **-50%** |-73% | -77% | **-91%** | +| Map-Grep | 7,189/s | 272% | 49% | 33% | -- | *-14%* | *-15%* | **-33%** |-64% | -69% | **-88%** | +| Flatten | *8,389/s* | *334%* | *74%* | *56%* | *17%* | *--* | *-1%* | -22% | *-58%* | *-63%* | ***-86%*** | +| Flatten-@ | *8,432/s* | *337%* | *75%* | *56%* | *17%* | *1%* | *--* | -22% | *-58%* | *-63%* | ***-86%*** | +| **Grep-@** | **10,764/s** | **457%** | **123%** | **100%** | **50%** | ***28%*** | ***28%*** | **--** | -46% | **-53%** | **-82%** | +| DNF | 20,080/s | 940% | 316% | 273% | 179% | *139%* | *138%* | **87%** | -- | -12% | **-67%** | +| Optimal | 22,936/s | 1,087% | 375% | 326% | 219% | *173%* | *172%* | **113%** | 14% | -- | **-62%** | +| **Hash-%** | **60,976/s** | **3,057%** | **1,164%** | **1,032%** | **748%** | ***627%*** | ***623%*** | **466%** | **204%** | **166%** | **--** | + # Challenge 2 - Ordered Letters **Given a word, you can sort its letters alphabetically (case insensitive). |