Airplane boarding puzzle

gistfile1.txt

Sample Output:

Airplane Boarding Problem
Ran simluation a total of 10000 times boarding 100 people per plane.

A total of 4970 of 10000 times (49.7%) the last passenger got their assigned seat.
The number of non-assigned passengers varied from 0 to 14 with an avg of 5.1828

Winners: 4970
The number of non-assigned passengers varied from 0 to 13 with an avg of 4.6796780684105

Losers: 5030
The number of non-assigned passengers varied from 2 to 14 with an avg of 5.6799204771372

puzzle.php

<?php

# https://medium.com/puzzle-sphere/can-you-solve-this-famous-interview-question-91d0db846935

echo "<h1>Airplane Boarding Problem</h1>" . "<pre>";

global $verbose;

// Set to true to print a lot more logging...
$verbose = false;

// This is the number of simulations you want to do
$sim_count = 10000;

// This is the number of passengers
$passenger_count = 100;

// A variable to hold results
$data = [];

// Loop through simulations
for ($i = 1; $i <= $sim_count; $i++) {
    // $i = current loop
    $result = [];
    $result['simulation'] = $i;
    $result['nonassigned_seat_count'] = 0;

    // Build an empty seatmap where key is seat number the value is the passenger 
    $result['seat_map'] = array_fill(1,$passenger_count,0);

    // Recursively board passengers
    $result = boardPassenger(1, $result);

    $data[$i] = $result;
}

echo "Ran simluation a total of $sim_count times boarding $passenger_count people per plane.\n\n";

// Look at how many times it was successful
$successes = array_sum(array_column($data, 'success'));
echo "A total of $successes of $sim_count times (" . round($successes/$sim_count*100,3) .
     "%) the last passenger got their assigned seat.\n";
printNonAssignedSeatCountData($data);

$winners = array_filter($data, fn($r)=> $r['success'] == 1);
echo "Winners: " . count($winners) . "\n";
printNonAssignedSeatCountData($winners);


$losers = array_filter($data, fn($r)=> $r['success'] == 0);
echo "Losers: " . count($losers) . "\n";
printNonAssignedSeatCountData($losers);




function printNonAssignedSeatCountData($arr) {
    $nasc = array_column($arr, 'nonassigned_seat_count');
    echo "The number of non-assigned passengers varied from " . min($nasc) . " to " . max($nasc) . 
    " with an avg of " . array_sum($nasc)/count($arr) . "\n\n";
}

function logIt($msg) {
    global $verbose;
    if ($verbose) echo "$msg\n";
}

function boardPassenger($passenger, $result) {

    $seat_count = count($result['seat_map']);


    $new_seat = $passenger;

    // Is assigned seat available? (For all but passenger 1)
    if ($result['seat_map'][$passenger] === 0 && $passenger !== 1) {

        // Assign person to assigned seat
        // $result['seat_map'][$passenger_number] = $passenger_number;
        logIt("Passenger $passenger seated in assigned seat");
    } else {
        // Randomly pick a seat for passenger
        // Step 1:  Get available seats (those with a value of 0)
        $available_seats = array_filter($result['seat_map'], fn($k) => $k == 0);
        logIt("There are " . count($available_seats) . " available seats");

        // Step 2:  Pick randomly
        $random_seat = array_rand($available_seats, 1);
        logIt("Selected random seat $random_seat");
        $new_seat = $random_seat;
    }

    $result['seat_map'][$new_seat] = $passenger;

    // Increment nonassigned_seat_count
    if ($new_seat !== $passenger) {
        $result['nonassigned_seat_count']++;
        logIt("Unassigned count incremented");
    }

    // See if we are done or if we need to continue
    if ($passenger == $seat_count) {
        // We are done - last passenger
        logIt("We are on last passenger -- returning");

        // Did we win?
        $result['success'] = ($passenger == $new_seat) ? 1 : 0;

        // End recursive loop
        return $result;
    } else {
        // Recurse to next passenger
        logIt("Goto next passenger - just sat $passenger in $new_seat");
        return boardPassenger(++$passenger, $result);
    }
}