<p>type RepeatString&lt;T extends string, C extends number, A extends any[] = [], S extends string = "" &gt; =
A["length"] extends C
? S
: RepeatString&lt;T,C,[...A,T],<code>${S}${T}</code>&gt;</p>
<p>type A = RepeatString&lt;'a', 3&gt; // 'aaa'
type B = RepeatString&lt;'a', 0&gt; // ''</p>

This is my accepted solution

Similar to String.prototype.repeat(), implement RepeatString<T, C> to create a new type by repeating string T for C times. type A = RepeatString<'a', …