function solution(begin, target, words) {
  let visited = new Array(words.length).fill(-1);
  let targetIndex = words.indexOf(target);
  let queue = [];
  if(targetIndex === -1) return 0;

  function bfs(queue) {
    while(queue.length) {
      const { word, level } = queue.shift();

      for(let i=0;i<words.length;i++) {
        let diff = 0;
        if(visited[i] !== -1 && visited[i]<=level) continue;
        for(let j = 0;j<word.length;j++) {
          if(words[i][j] !== word[j]) diff++;
          if(diff > 1) break;
        }
        if(diff === 1) {
          visited[i] = level + 1;
          if(words[i] === target) return;
          queue.push({word: words[i], level: level + 1});
        }
      }
    }
  }

  queue.push({word: begin, level: 0});

  bfs(queue);

  return visited[targetIndex]
}