[프로그래머스 Level 3] 단어 변환

function solution(begin, target, words) {
    const words_set = new Set(words);
 
    if(!words_set.has(target)) return 0;
 
    function getDiff(word1, word2, max_diff){
        let diff = 0;
 
        for(let i = 0; i < word1.length; i++){
            if(word1[i] !== word2[i]) diff++;
            if(max_diff && diff >= max_diff) return max_diff;
        }
 
        return diff;
    }
 
    function bfs(begin){
        const q = [ [begin, 0] ];
        const visited = new Set();
 
        while(q.length){
            const [word, steps] = q.shift();
 
            if(word === target) return steps;
 
            if(!visited.has(word)){
                visited.add(word);
 
                words_set.forEach(str => {
                    if(getDiff(str, word, 2) === 1 && !visited.has(str)) {
                        words_set.delete(str);
                        q.push([str, steps + 1]);
                    }
                });
            }
        }
        return 0;
    }
 
    return bfs(begin);
}