I'm making a Yahtzee game and I need a way to calculate a small straight (a sequence of 4 numbers in order). So valid ones would be: 1,2,3,4 | 2,3,4,5 | 3,4,5,6.
I have an array of 5 numbers and I need to figure out if one of those 3 combinations is in that array.
For those not familiar with Yahtzee, there are 5 dice (the five numbers in the array) that can be from 1-6.
function isStraight($hand) {
$straights = array(range(1, 4), range(2, 5), range(3, 6));
foreach($straights as $solution) {
if(array_intersect($solution, $hand) == $solution) {
return $solution;
}
}
return false;
}
$hand = array(1,5,2,4,3);
var_dump(isStraight($hand));
Not sure about the rules of the game, but that should do it.
The function is going to return the first solution it finds - in this case [1,2,3,4]. It is going to return the boolean false if it doesn't find any straights in the hand. Hope this helps.
Perhaps something like this: --- warning --- air coding
function findSequenceLength(array $array)
{
// Filter duplicates out - and sort the array.
$sorted = array_unique($array, SORT_NUMERIC);
$lastValue = null;
$thisSeq = 0;
$longestSeq = 0;
foreach ($sorted as $value)
{
if ( ( $lastValue !== null ) && $value == $lastValue + 1)
{
// our value is exactly one above the last entry
// increase the counter
$thisSeq++;
} else {
// sequence ended - save the value
$longestSeq = max($longestSeq, $thisSeq);
$thisSeq = 1;
}
$lastValue = $value;
}
return max($longestSeq, $thisSeq);
}
$sequence = array(1,2,4,5,4,6);
echo findSequenceLength($sequence); // should return 3 [4,5,6]
You could then test that the "sequence length" is >= 4 to test for your "small straight"
More precisely:
function array_match($array, $target_array) {
$offset = 0;
$maxoffset = sizeof($target_array) - sizeof($array);
for($y=0;$y<$maxoffset;$y++) {
$result = true;
for($x=0;$x<sizeof($array);$x++) {
if ($array[$x] != $target_array[$x+$y] ) {
$result = false;
continue;
}
}
if ($result)
return "true";
}
return "false";
}
echo array_match(array(1,2,3), array(1,2,3,4,5)); //true
echo array_match(array(1,2,3), array(4,1,2,3,5)); //true
echo array_match(array(1,2,3), array(4,2,2,1,2)); //false
Here's another idea, Use a generic isStraight() method and use it to test the two array slices.
$tests = array(
array(1,2,3,4,5),
array(1,1,2,3,4),
array(4,3,2,1,4),
array(3,4,5,6,1)
);
foreach($tests as $test) {
print_r($test);
echo "Straight: ";
var_dump(isStraight($test));
echo "Short Straight: ";
var_dump(isShortStraight($test));
echo "\n";
}
function isShortStraight($hand) {
return isStraight(array_slice($hand, 0, 4)) ||
isStraight(array_slice($hand, 1, 4));
}
function isStraight($hand) {
$unique = array_unique($hand);
if (count($hand) != count($unique)) {
/* Has Duplicates, not a straight */
return false;
}
sort($unique);
if ($unique != $hand) {
/* Sort order changed, not a straight */
return false;
}
return true;
}