breadth first search

'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', function(inputStdin) {
    inputString += inputStdin;
});

process.stdin.on('end', function() {
    inputString = inputString.split('\n');

    main();
});

function readLine() {
    return inputString[currentLine++];
}



/*
 * Complete the 'bfs' function below.
 *
 * The function is expected to return a STRING.
 * The function accepts following parameters:
 *  1. Vertex origin
 */

/*
 * For your reference:
 *
 * Vertex {
 *   char id;
 *   edges[Vertex];
 * }
 *
 */
function bfs(origin) {
  // Write your code here
  if (!origin) return ""
  let queue = []
  queue.push(origin)
  let output = []

  while (queue.length) {
    // process queue
    // add nodes to queue if not seen
    let current = queue.shift()
    if(output.includes(current.id)) continue
    output.push(current.id)
    let otherNodes = current.edges

    otherNodes.forEach(node => {
        queue.push(node)
    })

  }
  return output.join("")
}


function main() {