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| -rw-r--r-- | challenge-137/james-smith/README.md | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/challenge-137/james-smith/README.md b/challenge-137/james-smith/README.md index b32381ed19..9bdd58ce27 100644 --- a/challenge-137/james-smith/README.md +++ b/challenge-137/james-smith/README.md @@ -164,8 +164,15 @@ say $_ foreach sort { $a <=> $b } keys %lychrel; Using this script to generate all candidate Lychrel numbers up to 1 million took approximately `12` seconds. To use the `lychrel_large` routine took approximately 2180 seconds (36 minutes 20 seconds), a speed gain of approximately `180x`. -To 10 million the time taken was approximately 6 minutes. +To 10 million the time taken was approximately 1 min 40s; 20 million ~ 3 min 50s; 30 million ~ 31 min 40s {I think the time for this got large as the machine was starting to hit SWAP storage}. The code fails shortly after this as memory and swap was exhausted ~ 12GB. +| N | Lychrel < N | Time taken | +| ---------: | ----------: | ---------: | +| 10,000,000 | 2,010,871 | 1 min 40s | +| 20,000,000 | 4,521,930 | 3 min 50s | +| 30,000,000 | 7,177,742 | 31 min 40s | + +The last of these is still quicker than getting Lychrel numbers up to 1,000,000 using the "large" method. ### Explanation For every sequence generated above - all the numbers are either not Lychral numbers or candidate Lychral numbers. Once we either get to a palindrome OR reach the "end of the sequence" we can tag every number as either a candidate Lychral number or not. This reduces the number of calculations. |