답안

const graph = {
  'A': ['E', 'C', 'B'],
  'B': ['A'],
  'C': ['A'],
  'D': ['E','F'],
  'E': ['D', 'A'],
  'F': ['D'],
};


function dfs(graph, start){
  let visited = [];
  let stack = [start];

  while (stack.length !== 0){
    let n = stack.pop();
    if (!visited.includes(n)){
      visited.push(n);
      let sub = graph[n].filter(x => !visited.includes(x));
      for(let i of sub) {
        stack.push(i);
      }
    }
  }
  return visited;
}


console.log(dfs(graph, 'E'));