Parking at Hanoi - PhillyDev Slack #daily_programmer - 20170306

dp20170306.js

/*
There are N+1 parking spots, numbered from 0 to N. There are N cars numbered
from 1 to N parked in various parking spots with one left empty. Reorder the
cars so that car #1 is in spot #1, car #2 is in spot #2 and so on. Spot #0 will
remain empty. The only allowed operation is to take a car and move it to the
free spot.
*/

function initParking(size) {
  let parking = (new Array(size)).fill(null);
  let i = 1;
  while (i < parking.length) {
    let spot = Math.floor(Math.random() * (size + 1));
    if (parking[spot] === null) {
      parking[spot] = i++;
    }
  }

  return parking;
}

function reorderParking(parking) {
  console.log(0, parking);
  for (let i = 1; i < parking.length; i++) {
    if (parking[i] == i) {
      continue;
    }
    let emptySpot = parking.indexOf(null);
    if (emptySpot != i) {
      parking = swapParkingSpots(parking, emptySpot, i);
      console.log(i, parking);
    }
    let carSpot = parking.indexOf(i);
    parking = swapParkingSpots(parking, carSpot, i);
    console.log(i, parking);
  }

  return parking;
}

function swapParkingSpots(parking, i, j) {
  let tmp = parking[i];
  parking[i] = parking[j];
  parking[j] = tmp;

  return parking;
}

let size = Math.floor(Math.random() * (10 - 3)) + 3;
let result = reorderParking(initParking(size));