function solution(files) {
    const parseFile = file => {
        let head = ''
        let number = ''
        let tail = ''
                
        let current = 0;
        for(let i=0; i<file.length;i ++){
            const char = file[i]
            const code = char.charCodeAt();
            if(code > 47 && code <58){ // 숫자일 경우
                 number += char;
            }else{ // 숫자가 아닐 경우
                if(number.length > 0) break;
                head += char;
            }
        }
        
        return [head, number]
    }
    
    return files.map((file, i) =>{
        const [head, number] = parseFile(file)
        return ([{
                head: head.toLowerCase(), 
                number: +number}, i])
    }).sort((a,b) => {
        const fileA = a[0]
        const fileB = b[0]
        if(fileA.head > fileB.head) return 1
        if(fileA.head < fileB.head) return -1
        if(fileA.number > fileB.number) return 1
        if(fileA.number < fileB.number) return -1
        return 0
    }).map(([file, i]) => files[i])
}