FB Questions

FB Production Engineering Interview Question and Code:

import java.io.*;
import java.util.*;

/*
 * To execute Java, please define "static void main" on a class
 * named Solution.
 *
 * If you need more classes, simply define them inline.
 */

// dataset1.csv
// NAME,LEG_LENGTH,DIET
// T-Rex,1.3,carnivore

// dataset2.csv
// NAME,STRIDE_LENGTH,WALK_TYPE
// T-Rex,3.7,bipedal

// Output in sorted order the name and speed of all bipedal dinosaurs.

public static final double g = 9.8;

class Dinosaur {

  public class DiNode {
    String name;
    double stride_len;
    double leg_len;
    double speed;

    public DiNode(String name, double stride_len) {
      this.name = name;
      this.stride_len = stride_len;
      this.speed = Integer.MIN_VALUE;
    }

    public calculate_speed() {
      this.speed = ((stride_len/leg_len)/g);
    }

    public toString() {
      String s = "";
      s += this.name;
      s += this.speed;
      return s;
    }

  }


  public static void main(String[] args) {

    try {

      HashMap<String, DiNode> map = new HashMap<String, DiNode>();
      ArrayList<DiNode> list = new ArrayList<DiNode>();
      Scanner sc = new Scanner(new File("dataset2.csv"));
      String[] line;
      DiNode node;

      while (sc.hasNext()) {
        line = sc.next().split(",");
        // Error checks for args
        if (line[2].equals("bipedal")) {
          map.put(line[0], new DiNode(line[0], line[1]));
        }
      }

      sc.close();
      sc = new Scanner(new File("dataset1.csv"));

      while (sc.hasNext()) {
        line = sc.next().split(",");
        // Error checks for args
        node = map.get(line[0]);
        if (node != null) {
          node.leg_len = line[1];
          node.speed = node.calculate_speed();
        }
      }

      for (Map.Entry<String, DiNode> node : map) {
        if (node.speed != Integer.MIN_VALUE) {
          list.add(node);
        }
      }

      mergesort(list);

      for (DiNode node : list) {
        System.out.println(node);
      }

    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      sc.close();
    }

  }

}

2nd Q:
host range: web0001-1000.facebook.com
process name: app
optimal number of instances: 4

Assume authentication is not an issue.
Give me a list of all the hosts running the optimal number of instances of the given process.

def int_to_host():
	# ...Input 1, output web0001.facebook.com

list = [x for x in range(1,1000)]
host_list = map(int_to_host, list)
output = []

for host in host_list:
	if ssh(host, "ps aux | grep app | count -n") == 4:
		output.append(host)

print(output)