echo validatePIN("1234")."\n";
echo validatePIN("12345")."\n";
echo validatePIN("123456")."\n"; 
echo validatePIN("")."\n";

function validatePIN($pin){
	$len=strlen($pin);
	if (strlen($pin)!=4 && strlen($pin)!=6){
		return "PIN is invalid";
	}
	for ($i=0; $i<$len; $i++)
	$ASCII=ord($pin[$i]);
	if (!(47<$ASCII && $ASCII<58)){
		return "PIN is invalid";
	}
	return "PIN is valid";
}

/*
// a number "n" is automorphic if n^2 ends with "n"
e.g. 5 is automorphic number, because 5^2=25 ends with 5, 6^2=36 and is automorphic as well;
*/

echo "5 - ".isAutomorphic_2(5)."\n";    // 25
echo "8 - ".isAutomorphic_2(8)."\n";    // 64
echo "76 - ".isAutomorphic_2(76)."\n";  // 5,776

function isAutomorphic($num){
	$square=$num*$num;
	
	$result=str_ends_with($square, $num);
	return $result;
}


//using substring function
function isAutomorphic_2($num){
	return substr($num*$num, -1*strlen($num)) === strval($num);
}

echo rps("Rock", "Paper")."\n";
echo rps("Scissor", "Paper")."\n";
echo rps("Paper", "Paper")."\n";

function rps($p1, $p2){
	$res= "";
	if ($p1==$p2){
		$res="It's a draw";
	}else if (
		($p1=="Paper" && $p2=="Rock")||
		($p1=="Rock" && $p2=="Scissor")||
		($p1=="Scissor" && $p2=="Paper")
		){
			$res="Player 1 wins";
		}else {
			$res="Player 2 wins";
		}
		return $res;
}

print_r(splitCode("TEWA8392")); // ➞ ["TEWA", 8392]
print_r(splitCode("MMU778")); // ➞ ["MMU", 778]
print_r(splitCode("SRPE5532")); // ➞ ["SRPE", 5532]


function splitCode($code) {
	$alpha = $numbers = '';
	$len = strlen($code);
	for ($i=0; $i<$len; $i++) {
		if(!(47 < ord($code[$i])&&ord($code[$i]) < 58)) {
		// if(!is_numeric($code[$i])) {
			$alpha.=$code[$i];
		} else {
			$numbers = substr($code, $i);
			break;
		}
	}
	return [$alpha, $numbers];
}

//An array is special if every even index contains an even number and every odd index contains an odd number. 
var_dump(isSpecialArray([2, 7, 4, 9, 6, 1, 6, 3]));//➞ true
var_dump(isSpecialArray([2, 7, 9, 1, 6, 1, 6, 3]));//➞ false
var_dump(isSpecialArray([2, 7, 8, 8, 6, 1, 6, 3]));//➞ false

function isSpecialArray($array){
	foreach($array as $key=>$value){
		if($key%2+$value%2==1){
			return "Array is not special";
		}
	}
	return "Array is special";
}

echo correctSpacing_1(" my   name   is Slim Shady  ")."\n";
echo correctSpacing_2(" my   name   is Giovani Giorgio  ")."\n";

//Using explode function
function correctSpacing_1($sentence) {
	$array = explode(' ', $sentence);
	$count = count($array);
	for ($i = 0; $i < $count; $i++) {
		if (!$array[$i]) {
			unset ($array[$i]);
		}
	}
	return implode(' ', $array);
}

//Using while loop
function correctSpacing_2($sentence) {
	$sentence = trim($sentence);
	while (str_contains($sentence, '  ')) {
		$sentence = str_replace('  ', ' ', $sentence);
	}
	return $sentence;
}

var_dump(isValidHexCode("#CD5C5C")); // ➞ true
var_dump(isValidHexCode("#EAECEE")); // ➞ true
var_dump(isValidHexCode("#eaecee")); // ➞ true
var_dump(isValidHexCode("#CD5C58C")); // ➞ false
// Length exceeds 6
var_dump(isValidHexCode("#CD5C5Z")); // ➞ false
// Not all alphabetic characters in A-F
var_dump(isValidHexCode("#CD5C&C")); // ➞ false
// Contains unacceptable character
var_dump(isValidHexCode("CD5C5C")); // ➞ false
// Missing #


function isValidHexCode($code) {
	$allowed = '0123456789abcdef';
	$len = strlen($code);
	if ($len!=7 || $code[0]!='#') {
		return false;
	}
	for ($i=1; $i<$len; $i++) {
		if (!str_contains($allowed, strtolower($code[$i]))) {
			return false;
		}
	}
	return true;
}

echo century(1756)."\n";
echo century(1555)."\n";
echo century(1000)."\n";
echo century(1001)."\n";
echo century(2005)."\n";


// Get the Century
function century($year) {
	$suf = 'th';
	if ($year > 2000) {
		$suf = 'st';
	}
	return ceil($year/100).$suf.' century';
}

print_r(findPrimeNumbers(50));

//Prime numbers are evenly divided by themselves and by one
//Finds first N prime number
function findPrimeNumbers($n){
	$num=2;//first  prime number is 2
	$res=[];
	while  (0<$n){
		$cnt=0;
		for ($i=2; $i<=$num; $i++){
			if ($num%$i==0){
				$cnt++;
			}
		}
		if ($cnt==1){
			$res[]=$num;
			$n--;
		}
		$num++;
	}
	return $res;
}

echo "6 - ".checkNumber(6)."\n\n";
echo "9 - ".checkNumber(9)."\n\n";
echo "12 - ".checkNumber(12)."\n\n";

function checkNumber($num) {
	$res = 'Deficient';

	if ($num == 1) {
		return false;
	}

	$sqrt = sqrt($num);

	$sum = 1;
	// Loops starting 2 to the square root of the given number
	for ($i = 2; $i <= $sqrt; $i++) {
		if ($num%$i == 0) {
			$sum += $i;

			$result = $num/$i;
			// If $i is not equal to the square root,
			// then adds it to the $sum variable
			if ($result != $i) {
				$sum += $result;
			}
		}
	}
	if ($sum == $num) {
		$res = 'Perfect';
	} else if ($sum > $num) {
		$res = 'Abundant';
	}
	return $res;
}