6 ms·

The next question I like to ask in an interview, once they have fizzbuzz working is, "Now make it more efficient."

deleted 8y ago
[deleted]
edflsafoiewq 8y ago
echo '#include <stdio.h>' > fb.c ./fizzbuzz > buf xxd -i buf >> fb.c echo 'int main(void) { return fwrite(buf, buf_len, 1, stdout) != 1; }' >> fb.c
AndyKelley 8y ago
Zig: const std = @import("std"); pub fn main() u8 { @setEvalBranchQuota(2000); const precomputed_output = comptime fizzbuzz: { var s: []const u8 = ""; var i: usize = 1; while (i <= 100) : (i += 1) { if (i % 3 == 0 and i % 5 == 0) { s = s ++ "FizzBuzz\n"; } else if (i % 3 == 0) { s = s ++ "Fizz\n"; } else if (i % 5 == 0) { s = s ++ "Buzz\n"; } else { var buf: [20]u8 = undefined; const n = buf[0..std.fmt.formatIntBuf(&buf, i, 10, false, 0)]; s = s ++ n ++ "\n"; } } break :fizzbuzz s; }; const stdout = std.io.getStdOut() catch return 1; stdout.write(precomputed_output) catch return 1; return 0; } Output: $ zig build-exe fizzbuzz.zig $ ./fizzbuzz <correct output> $ strace ./fizzbuzz execve("./fizzbuzz", ["./fizzbuzz"], 0x7ffeeb1a4540 /* 132 vars */) = 0 write(1, "1\n2\nFizz\n4\nBuzz\nFizz\n7\n8\nFizz\nBu"..., 4131 exit(0) = ? The entire program is 1 write syscall that outputs the answer. I don't think it's theoretically possible to get faster than that.
- loeg 8y ago
  > The entire program is 1 write syscall that outputs the answer. I don't think it's theoretically possible to get faster than that. If stdout happens to be a socket, setsockopt + SO_SNDBUF might help runtime. But that is an extremely byzantine scenario. Another consideration might be a fast CPU attached to a fast but tiny icache and dcache with very slow memory, where reading the pregenerated string is slower than computing it.
leifmetcalf 8y ago
With this? http://duriansoftware.com/joe/Optimizing-is-multiple-checks-with-modular-arithmetic.html http://duriansoftware.com/joe/Optimizing-is-multiple-checks-...
a3n 8y ago
In time or in (disk | memory) space?

deleted 8y ago

[deleted]

echo '#include <stdio.h>' > fb.c ./fizzbuzz > buf xxd -i buf >> fb.c echo 'int main(void) { return fwrite(buf, buf_len, 1, stdout) != 1; }' >> fb.c

AndyKelley 8y ago

Zig: const std = @import("std"); pub fn main() u8 { @setEvalBranchQuota(2000); const precomputed_output = comptime fizzbuzz: { var s: []const u8 = ""; var i: usize = 1; while (i <= 100) : (i += 1) { if (i % 3 == 0 and i % 5 == 0) { s = s ++ "FizzBuzz\n"; } else if (i % 3 == 0) { s = s ++ "Fizz\n"; } else if (i % 5 == 0) { s = s ++ "Buzz\n"; } else { var buf: [20]u8 = undefined; const n = buf[0..std.fmt.formatIntBuf(&buf, i, 10, false, 0)]; s = s ++ n ++ "\n"; } } break :fizzbuzz s; }; const stdout = std.io.getStdOut() catch return 1; stdout.write(precomputed_output) catch return 1; return 0; } Output: $ zig build-exe fizzbuzz.zig $ ./fizzbuzz <correct output> $ strace ./fizzbuzz execve("./fizzbuzz", ["./fizzbuzz"], 0x7ffeeb1a4540 /* 132 vars */) = 0 write(1, "1\n2\nFizz\n4\nBuzz\nFizz\n7\n8\nFizz\nBu"..., 4131 exit(0) = ? The entire program is 1 write syscall that outputs the answer. I don't think it's theoretically possible to get faster than that.

loeg 8y ago
> The entire program is 1 write syscall that outputs the answer. I don't think it's theoretically possible to get faster than that. If stdout happens to be a socket, setsockopt + SO_SNDBUF might help runtime. But that is an extremely byzantine scenario. Another consideration might be a fast CPU attached to a fast but tiny icache and dcache with very slow memory, where reading the pregenerated string is slower than computing it.

leifmetcalf 8y ago

With this? http://duriansoftware.com/joe/Optimizing-is-multiple-checks-with-modular-arithmetic.html http://duriansoftware.com/joe/Optimizing-is-multiple-checks-...

a3n 8y ago

In time or in (disk | memory) space?