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发表于 2013-10-14 13:03:36
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来自 北京西城
本帖最后由 chyanog 于 2013-10-14 13:13 编辑
- Tr@N@DeleteDuplicates[Join @@ Range[0, 1*^7 - 1, {3, 5}]] // AbsoluteTiming
- Tr@N@Pick[#, #~Mod~3*#~Mod~5, 0] &@Range[1*^7 - 1] // AbsoluteTiming
- n /. Solve[{n~Mod~3 n~Mod~5 == 0, 0 < n < 1000}, n, Integers] // Total
- Sum[Boole[Mod[i, 3] == 0 || Mod[i, 5] == 0] i, {i, n}]
- Sum[(Boole[Mod[i, 3] == 0] + Boole[Mod[i, 5] == 0] -Boole[Mod[i, 15] == 0]) i, {i, n}] // Simplify
- tic,n=1e7-1;sum(unique([int32(0:3:n), int32(0:5:n)])),toc
- tic,a=int32(1:1e7-1);sum(a(mod(a,3)==0 | mod(a,5)==0)),toc
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