good kata for learning things about chains

When your result looks like the expected one, but still fails, it is helpful to print your string between delimiters and escape whitespace characters.

For your situation:

String s = sb.toString();
System.out.print('"');
for (int i = 0; i < s.length(); i++) {
    char ch = s.charAt(i);
    System.out.print(ch == '\n' ? "\\n" : Character.toString(ch));
}
System.out.print('"');

for n = 1, this prints:

"*\n \n"

while the expected answer is:

"*\n"

The problem comes from your code. You are casting a negative number to usize, which results in a really big unsigned number. And then you use this number as the bound in a loop in which you allocate memory, hence the allocation failure.

Return null/nil/None/... if the input is an even number or negative, as it is not possible to print a diamond of even or negative size.

My Rust solution should work, but adding the appropriately placed newline characters gives this result. This only pops up when the answer is correct - if I add a newline character at the start of the string, the test fails and no error occurs.

memory allocation of 9223372036854775806 bytes failed

Caused by:
process didn't exit successfully: /workspace/target/debug/deps/challenge-07bd72047d917620 --show-output -Z unstable-options --format json (signal: 6, SIGABRT: process abort signal)

This one really took a toll on me! TvT

Thank you so much for your sugestion! I rewrote the code with an empty array concating other arrays and it worked:)

try your code with a string that has no 'a', but that has other vowels

Also:

• you can print the input to debug your code (e.g. console.log(str);)
• use markdown formatting when you post code

Language?

The registers to use r unclear: idek where the string is located

I'm kindof sad that regexp_count is not available in postgres 13.

Approved