diff options
| author | Denys Vlasenko <vda.linux@googlemail.com> | 2020-12-22 20:08:40 +0100 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2020-12-22 20:24:30 +0100 |
| commit | 6452c300366cf0e322227ad39991ec2fdfd6beed (patch) | |
| tree | d2086c915ebeddea5775aa66e0dc07dae41addc2 /testsuite | |
| parent | 96717d9fb4560ad98a737108f83c7b247ef04674 (diff) | |
| download | busybox-6452c300366cf0e322227ad39991ec2fdfd6beed.tar.gz | |
factor: detect squares
If we have a square, the speedup can be extremely large
(in best case example below, it's ~40000 times faster):
$ time ./busybox_old factor 18446743988964486098
18446743988964486098: 2 3037000493 3037000493
real 0m4.246s
$ time ./busybox factor 18446743988964486098
18446743988964486098: 2 3037000493 3037000493
real 0m0.000s
function old new delta
isqrt_odd - 57 +57
print_w - 36 +36
factorize 218 236 +18
print_h - 7 +7
factorize_numstr 65 72 +7
------------------------------------------------------------------------------
(add/remove: 3/0 grow/shrink: 2/0 up/down: 125/0) Total: 125 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'testsuite')
| -rwxr-xr-x | testsuite/factor.tests | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/testsuite/factor.tests b/testsuite/factor.tests index 2cf4a54ce..e404e29c1 100755 --- a/testsuite/factor.tests +++ b/testsuite/factor.tests @@ -45,4 +45,27 @@ testing "factor \$((2*3*5*7*11*13*17*19*23*29*31*37*41*43*47))" \ "614889782588491410: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47\n" \ "" "" +# Test that square-detection code is not buggy +testing "factor 2 * 3037000493 * 3037000493" \ + "factor 18446743988964486098" \ + "18446743988964486098: 2 3037000493 3037000493\n" \ + "" "" +testing "factor 3 * 2479700513 * 2479700513" \ + "factor 18446743902517389507" \ + "18446743902517389507: 3 2479700513 2479700513\n" \ + "" "" +# including square-of-square cases: +testing "factor 3 * 37831 * 37831 * 37831 * 37831" \ + "factor 6144867742934288163" \ + "6144867742934288163: 3 37831 37831 37831 37831\n" \ + "" "" +testing "factor 3 * 13^16" \ + "factor 1996249827549539523" \ + "1996249827549539523: 3 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13\n" \ + "" "" +testing "factor 13^16" \ + "factor 665416609183179841" \ + "665416609183179841: 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13 13\n" \ + "" "" + exit $FAILCOUNT |