* Iteration 5:
* $result = 54321 (5432 * 10 + 1.2345 % 10)
* $number = 0.12345
*
* @param int $number
* @return int
* @throws \InvalidArgumentException
*/
function reverseDigits($number)
{
if (!is_int($number)) {
throw new \InvalidArgumentException('$number must be an integer');
}
$isNegative = $number < 0;
$number = abs($number);
$result = 0;
while ($number >= 1) {
$result = $result * 10 + $number % 10;
// Known issue, working with very large numbers will cause issues. i.e. PHP_INT_MAX
$number = $number / 10;
}
if ($isNegative) {
$result *= -1;
}
return $result;
}
$inputHelper = new InputHelper();
$number = $inputHelper->readInputFromStdIn('Enter the integer to reverse: ');
$result = reverseDigits((int) $number);
printf('The result of reversing the digits in %d is: %d', (int) $number, $result);
print PHP_EOL;
* 65 = 1000001
* 1000001 / result = 1
* 1000000 / result = 0
* parity of 65 is 0
*
* This improves performance in the best and average cases but can still be as slow as brute force. For example if run
* on 9223372036854775807 it will take 63 iterations which matches brute force.
*
* @param int $number
* @return int
* @throws \InvalidArgumentException
*/
function computeParityEraseLowestSetBit($number)
{
if (!is_int($number)) {
throw new \InvalidArgumentException('$number must be an integer');
}
$bitwiseHelper = new BitwiseHelper();
$number = $bitwiseHelper->eraseSignBit($number);
$result = 0;
while ($number) {
$result ^= 1;
$number &= $number - 1;
}
return $result;
}
$inputHelper = new InputHelper();
$number = $inputHelper->readInputFromStdIn('Enter an integer: ');
$parity = computeParityEraseLowestSetBit((int) $number);
printf('The parity of %d is %d', $number, $parity);
print PHP_EOL;
* return true
*
* @param int[] $array
* @param int $t
* @return bool
*/
function hasTwoSum($array, $t)
{
$j = 0;
$k = count($array) - 1;
while ($j <= $k) {
if ($array[$j] + $array[$k] == $t) {
return true;
} elseif ($array[$j] + $array[$k] < $t) {
$j++;
} else {
$k--;
}
}
return false;
}
$inputHelper = new InputHelper();
$array = json_decode($inputHelper->readInputFromStdIn('Enter the array of numbers as a json encoded array: '));
$t = (int) $inputHelper->readInputFromStdIn('Enter the number to test for 3-sum: ');
$result = hasThreeSum($array, $t);
if ($result) {
printf('The array %s can be 3-summed for %d', json_encode($array), $t);
} else {
printf('The array %s can not be 3-summed for %d', json_encode($array), $t);
}
print PHP_EOL;
* If the two rectangles are {x: 2, y: 1, width: 2, height: 2} and {x: 3, y: 0, width: 4, height: 2}
*
* Is the first rectangles x-coordinate(2) <= the second rectangles x-coordinate(3) + the second rectangles width(4) = 7? YES
* Is the first rectangles x-coordinate(2) + the first rectangles width(2) = 4 >= the second rectangles x-coordinate(3)? YES
* Is the first rectangles y-coordinate(1) <= the second rectangles y-coordinate(0) + the second rectangles height(2) = 2? YES
* Is the first rectangles y-coordinate(1) + the first rectangles height(2) = 3 >= the second rectangles y-coordinate(0)? YES
*
* They intersect
*
* @param Rectangle $firstRectangle
* @param Rectangle $secondRectangle
* @return bool
*/
function rectanglesIntersect(Rectangle $firstRectangle, Rectangle $secondRectangle)
{
return $firstRectangle->getX() <= $secondRectangle->getX() + $secondRectangle->getWidth() && $firstRectangle->getX() + $firstRectangle->getWidth() >= $secondRectangle->getX() && $firstRectangle->getY() <= $secondRectangle->getY() + $secondRectangle->getHeight() && $firstRectangle->getY() + $firstRectangle->getHeight() >= $secondRectangle->getY();
}
$inputHelper = new InputHelper();
$firstX = (int) $inputHelper->readInputFromStdIn('Enter the x coordinate of the first rectangle: ');
$firstY = (int) $inputHelper->readInputFromStdIn('Enter the y coordinate of the first rectangle: ');
$firstWidth = (int) $inputHelper->readInputFromStdIn('Enter the width of the first rectangle: ');
$firstHeight = (int) $inputHelper->readInputFromStdIn('Enter the height of the first rectangle: ');
$secondX = (int) $inputHelper->readInputFromStdIn('Enter the x coordinate of the second rectangle: ');
$secondY = (int) $inputHelper->readInputFromStdIn('Enter the y coordinate of the second rectangle: ');
$secondWidth = (int) $inputHelper->readInputFromStdIn('Enter the width of the second rectangle: ');
$secondHeight = (int) $inputHelper->readInputFromStdIn('Enter the height of the second rectangle: ');
$firstRectangle = new Rectangle($firstX, $firstY, $firstWidth, $firstHeight);
$secondRectangle = new Rectangle($secondX, $secondY, $secondWidth, $secondHeight);
$result = getIntersectingRectangle($firstRectangle, $secondRectangle);
printf('The intersection of rectangles %s and %s is %s', $firstRectangle, $secondRectangle, $result);
print PHP_EOL;
* @param array $words
* @return array
*/
function partitionIntoAnagramGroups($words = [])
{
if (empty($words)) {
return [];
}
$sortedWordsToWords = [];
$anagramGroups = [];
foreach ($words as $word) {
// There is no built in string sort so we convert the string to an array, sort it and convert it back to a
// string.
$sortedWord = str_split($word);
sort($sortedWord);
$sortedWord = implode('', $sortedWord);
$sortedWordsToWords[$sortedWord][] = $word;
}
foreach ($sortedWordsToWords as $sortedWord => $words) {
// A group must have more than one entry
if (count($words) > 1) {
$anagramGroups[] = $words;
}
}
return $anagramGroups;
}
$inputHelper = new InputHelper();
$words = explode(' ', $inputHelper->readInputFromStdIn('Enter the words separated by spaces: '));
$result = partitionIntoAnagramGroups($words);
printf('The groups of anagrams formed from %s are %s.', json_encode($words), json_encode($result));
print PHP_EOL;
*
* $intersection = [2, 4]
*
* @param array $array1
* @param array $array2
* @return array
*/
function computeIntersectionUsingLinearAdvancement($array1 = [], $array2 = [])
{
$i = 0;
$j = 0;
$intersection = [];
while ($i < count($array1) && $j < count($array2)) {
if ($array1[$i] == $array2[$j] && ($i == 0 || $array1[$i] != $array1[$i - 1])) {
$intersection[] = $array1[$i];
$i++;
$j++;
} elseif ($array1[$i] < $array2[$j]) {
$i++;
} else {
$j++;
}
}
return $intersection;
}
$inputHelper = new InputHelper();
$array1 = json_decode($inputHelper->readInputFromStdIn('Enter the first array in json format: '));
$array2 = json_decode($inputHelper->readInputFromStdIn('Enter the second array in json format: '));
$result = computeIntersection($array1, $array2);
printf('The intersection of %s and %s is %s', json_encode($array1), json_encode($array2), json_encode($result));
print PHP_EOL;
*/
function findClosestIntegerWithTheSameWeight($number)
{
if (!is_int($number)) {
throw new \InvalidArgumentException('$number must be an integer');
}
if ($number < 0) {
throw new \InvalidArgumentException('$number must be non-negative');
}
$integerWidth = PHP_INT_SIZE * BitwiseHelper::WORD_SIZE;
// Ignore the last bit as it's the sign bit (0 - 62 is 63 bits and 0 - 30 is 31 bits)
for ($i = 0; $i < $integerWidth - 2; $i++) {
// If the bits at position i and i + 1 are not the same
if ($number >> $i & 1 ^ $number >> $i + 1 & 1) {
// Swap the bits
$number ^= 1 << $i | 1 << $i + 1;
return $number;
}
}
throw new \RuntimeException('all bits of $number are 0 or 1');
}
$inputHelper = new InputHelper();
$number = $inputHelper->readInputFromStdIn('Enter a non-negative integer: ');
try {
$result = findClosestIntegerWithTheSameWeight((int) $number);
printf('The closest integer to %d (%b) with the same weight is %d (%b)', $number, $number, $result, $result);
print PHP_EOL;
} catch (\RuntimeException $e) {
printf('All of the bits in %d (%b) are 0 or 1', $number, $number);
print PHP_EOL;
}
* <<< SECOND RECURSIVE CALL BEGIN >>>
* $numberOfRings = 0
* $fromPeg = 2
* $toPeg = 1
* $usePeg = 0
*
* Is $numberOfRings > 0? No
* <<< SECOND RECURSIVE CALL RETURN >>>
* <<< SECOND RECURSIVE CALL RETURN >>>
* <<< SECOND RECURSIVE CALL RETURN >>>
*
* @param int $numberOfRings
* @param array[\SplStack] $pegs
* @param int $fromPeg
* @param int $toPeg
* @param int $usePeg
*/
function printTowerOfHanoiSteps($numberOfRings, $pegs, $fromPeg, $toPeg, $usePeg)
{
if ($numberOfRings > 0) {
printTowerOfHanoiSteps($numberOfRings - 1, $pegs, $fromPeg, $usePeg, $toPeg);
printf('Move %d from peg %d to peg %d', $pegs[$fromPeg]->top(), $fromPeg, $toPeg);
print PHP_EOL;
$pegs[$toPeg]->push($pegs[$fromPeg]->top());
$pegs[$fromPeg]->pop();
printTowerOfHanoiSteps($numberOfRings - 1, $pegs, $usePeg, $toPeg, $fromPeg);
}
}
$inputHelper = new InputHelper();
$numberOfRings = (int) $inputHelper->readInputFromStdIn('Enter the number of rings to move: ');
computeTowerOfHanoiMoves($numberOfRings);
$start = (int) $start;
$end = (int) $end;
$range = $end - $start + 1;
do {
$result = 0;
// Make sure that if 1 << $i is less than zero we stop. Otherwise we will loop forever
for ($i = 0; 1 << $i < $range && 1 << $i > 0; $i++) {
$result = $result << 1 | rand(0, 1);
}
} while ($result >= $range);
return $result + $start;
}
if (false) {
$results = [1 => 0, 2 => 0, 3 => 0, 4 => 0, 5 => 0];
$tests = 10000;
for ($i = 0; $i < $tests; $i++) {
$results[generateUniformRandomNumber(1, 5)]++;
}
print 'Tests run: ' . $tests . PHP_EOL;
foreach ($results as $value => $count) {
printf('Percentage of %d\'s: %f', $value, $count / $tests * 100);
print PHP_EOL;
}
} else {
$inputHelper = new InputHelper();
$start = $inputHelper->readInputFromStdIn('Enter the start integer: ');
$end = $inputHelper->readInputFromStdIn('Enter the end integer: ');
$result = generateUniformRandomNumber($start, $end);
printf('Random value between %d and %d inclusive: %d', $start, $end, $result);
print PHP_EOL;
}
* @throws \InvalidArgumentException
*/
function swapBits($number, $index1, $index2)
{
if (!is_int($number) || !is_int($index1) || !is_int($index2)) {
throw new \InvalidArgumentException('$number, $index1 and $index2 must all be integers');
}
if ($index1 < 0 || $index2 < 0) {
throw new \InvalidArgumentException('$index1 and $index2 must be greater than 0');
}
// Don't let the sign bit be swapped
if (PHP_INT_SIZE == 8 && ($index1 > 62 || $index2 > 62)) {
throw new \InvalidArgumentException('$index1 and $index2 must be less than or equal to 63');
}
// Don't let the sign bit be swapped
if (PHP_INT_SIZE == 4 && ($index1 > 30 || $index2 > 30)) {
throw new \InvalidArgumentException('$index1 and $index2 must be less than or equal to 31');
}
// See if the bits differ
if (($number >> $index1 & 1) != ($number >> $index2 & 1)) {
$number ^= 1 << $index1 | 1 << $index2;
}
return $number;
}
$inputHelper = new InputHelper();
$number = $inputHelper->readInputFromStdIn('Enter an integer: ');
$index1 = $inputHelper->readInputFromStdIn('Enter index 1 in the swap: ');
$index2 = $inputHelper->readInputFromStdIn('Enter index 2 in the swap: ');
$result = swapBits((int) $number, (int) $index1, (int) $index2);
printf('The result of swapping the %d and %d bits of %b (%d) is %b (%d)', $index1, $index2, $number, $number, $result, $result);
print PHP_EOL;
*
* @param int[] $array
* @param int $t
* @return bool
*/
function hasTwoSum($array, $t)
{
$j = 0;
$k = count($array) - 1;
while ($j <= $k) {
if ($array[$j] + $array[$k] == $t) {
return true;
} elseif ($array[$j] + $array[$k] < $t) {
$j++;
} else {
$k--;
}
}
return false;
}
$inputHelper = new InputHelper();
$array = json_decode($inputHelper->readInputFromStdIn('Enter the array of numbers as a json encoded array: '));
$k = json_decode($inputHelper->readInputFromStdIn('Enter the number of elements to add for the sum: '));
$t = (int) $inputHelper->readInputFromStdIn('Enter the number to test for ' . $k . '-sum: ');
$result = hasKSum($array, $t, $k);
if ($result) {
printf('The array %s can be ' . $k . '-summed for %d', json_encode($array), $t);
} else {
printf('The array %s can not be ' . $k . '-summed for %d', json_encode($array), $t);
}
print PHP_EOL;
throw new \InvalidArgumentException('$integer must be a number');
}
$integer = (int) $integer;
if ($integer < 0) {
return false;
}
if ($integer === 0) {
return true;
}
$numberOfDigits = floor(log10($integer)) + 1;
$integerRemaining = $integer;
$msdShift = pow(10, $numberOfDigits - 1);
for ($i = 0; $i < $numberOfDigits / 2; $i++) {
if ((int) ($integer / $msdShift) != (int) ($integerRemaining % 10)) {
return false;
}
$integer %= $msdShift;
$msdShift /= 10;
$integerRemaining /= 10;
}
return true;
}
$inputHelper = new InputHelper();
$integer = $inputHelper->readInputFromStdIn('Enter the integer to test: ');
$result = isPalindromic($integer);
if ($result === true) {
printf('The integer %d is palindromic', $integer);
} else {
printf('The integer %d is not palindromic', $integer);
}
print PHP_EOL;
if ($score < 0 || $score > PHP_INT_MAX || !is_int($score)) {
throw new \InvalidArgumentException('$score must be an integer between 0 and ' . PHP_INT_MAX);
}
if (!is_array($plays) || empty($plays)) {
throw new \InvalidArgumentException('$plays must be a non-empty array');
}
$permutations = array_fill(0, $score + 1, 0);
// There is only one way to score 0 points
$permutations[0] = 1;
for ($i = 0; $i <= $score; $i++) {
foreach ($plays as $play) {
if ($play < 0) {
throw new \InvalidArgumentException('negative value plays are not handled');
}
// If the play can achieve the current score
if ($i >= $play) {
$permutations[$i] += $permutations[$i - $play];
}
}
}
return $permutations[$score];
}
$inputHelper = new InputHelper();
$score = (int) $inputHelper->readInputFromStdIn('Enter the aggregate score: ');
$plays = json_decode($inputHelper->readInputFromStdIn('Enter the set of plays as a json encoded array: '));
$combinations = computeCombinations($score, $plays);
$permutations = computePermutations($score, $plays);
printf('The combinations to achieve an aggregate score of %d using plays that can score %s is %d', $score, json_encode($plays), $combinations);
print PHP_EOL;
printf('The permutations to achieve an aggregate score of %d using plays that can score %s is %d', $score, json_encode($plays), $permutations);
print PHP_EOL;