cur
조회function gcdOfStrings(str1: string, str2: string): string {
let result = ''
for(let i = 0; i < str1.length; i++) {
const cur = str1.slice(0, i + 1)
if(str1.replaceAll(cur, '')) continue
if(str2.replaceAll(cur, '')) continue
result = cur
}
return result
};