好的，这是我的看法，下面的代码将整个原始数组拆分为最长的相邻非重叠块。
所以在这种情况下
'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'c', 'd'
[ ] [ ] [ ] [ ] <-- use 2 long groups
[ ] [ ] [ ] [ ] [ ] [ ] <-- and not 4 short
它会更喜欢 2 个长组而不是 4 个短组。
更新：还使用来自另一个答案的示例进行了测试，也适用于这些情况：
one, two, one, two, one, two, one, two
[one two one two], [one two one two]
'one' 'two' 'one' 'two' 'three' 'four' 'one' 'two' 'three' 'four'
['one'] ['two'] ['one' 'two' 'three' 'four'] ['one' 'two' 'three' 'four']
这里是代码和测试：
<?php
/*
* Splits an $array into chunks of $chunk_size.
* Returns number of repeats, start index and chunk which has
* max number of ajacent repeats.
*/
function getRepeatCount($array, $chunk_size) {
$parts = array_chunk($array, $chunk_size);
$maxRepeats = 1;
$maxIdx = 0;
$repeats = 1;
$len = count($parts);
for ($i = 0; $i < $len-1; $i++) {
if ($parts[$i] === $parts[$i+1]) {
$repeats += 1;
if ($repeats > $maxRepeats) {
$maxRepeats = $repeats;
$maxIdx = $i - ($repeats-2);
}
} else {
$repeats = 1;
}
}
return array($maxRepeats, $maxIdx*$chunk_size, $parts[$maxIdx]);
}
/*
* Finds longest pattern in the $array.
* Returns number of repeats, start index and pattern itself.
*/
function findLongestPattern($array) {
$len = count($array);
for ($window = floor($len/2); $window >= 1; $window--) {
$num_chunks = ceil($len/$window);
for ($i = 0; $i < $num_chunks; $i++) {
list($repeats, $idx, $pattern) = getRepeatCount(
array_slice($array, $i), $window
);
if ($repeats > 1) {
return array($repeats, $idx+$i, $pattern);
}
}
}
return array(1, 0, [$array[0]]);
}
/*
* Splits $array into longest adjacent non-overlapping parts.
*/
function splitToPatterns($array) {
if (count($array) < 1) {
return $array;
}
list($repeats, $start, $pattern) = findLongestPattern($array);
$end = $start + count($pattern) * $repeats;
return array_merge(
splitToPatterns(array_slice($array, 0, $start)),
array(
array('number'=>$repeats, 'values' => $pattern)
),
splitToPatterns(array_slice($array, $end))
);
}
测试：
function isEquals($expected, $actual) {
$exp_str = json_encode($expected);
$act_str = json_encode($actual);
$equals = $exp_str === $act_str;
if (!$equals) {
echo 'Equals check failed'.PHP_EOL;
echo 'expected: '.$exp_str.PHP_EOL;
echo 'actual : '.$act_str.PHP_EOL;
}
return $equals;
}
assert(isEquals(
array(1, 0, ['a']), getRepeatCount(['a','b','c'], 1)
));
assert(isEquals(
array(1, 0, ['a']), getRepeatCount(['a','b','a','b','c'], 1)
));
assert(isEquals(
array(2, 0, ['a','b']), getRepeatCount(['a','b','a','b','c'], 2)
));
assert(isEquals(
array(1, 0, ['a','b','a']), getRepeatCount(['a','b','a','b','c'], 3)
));
assert(isEquals(
array(3, 0, ['a','b']), getRepeatCount(['a','b','a','b','a','b','a'], 2)
));
assert(isEquals(
array(2, 2, ['a','c']), getRepeatCount(['x','c','a','c','a','c'], 2)
));
assert(isEquals(
array(1, 0, ['x','c','a']), getRepeatCount(['x','c','a','c','a','c'], 3)
));
assert(isEquals(
array(2, 0, ['a','b','c','d']),
getRepeatCount(['a','b','c','d','a','b','c','d','c','d'],4)
));
assert(isEquals(
array(2, 2, ['a','c']), findLongestPattern(['x','c','a','c','a','c'])
));
assert(isEquals(
array(1, 0, ['a']), findLongestPattern(['a','b','c'])
));
assert(isEquals(
array(2, 2, ['c','a']),
findLongestPattern(['a','b','c','a','c','a'])
));
assert(isEquals(
array(2, 0, ['a','b','c','d']),
findLongestPattern(['a','b','c','d','a','b','c','d','c','d'])
));
// Find longest adjacent non-overlapping patterns
assert(isEquals(
array(
array('number'=>1, 'values'=>array('a')),
array('number'=>1, 'values'=>array('b')),
array('number'=>1, 'values'=>array('c')),
),
splitToPatterns(['a','b','c'])
));
assert(isEquals(
array(
array('number'=>1, 'values'=>array('a')),
array('number'=>1, 'values'=>array('b')),
array('number'=>2, 'values'=>array('c','a')),
),
splitToPatterns(['a','b','c','a','c','a'])
));
assert(isEquals(
array(
array('number'=>2, 'values'=>array('a','b','c','d')),
array('number'=>1, 'values'=>array('c')),
array('number'=>1, 'values'=>array('d')),
),
splitToPatterns(['a','b','c','d','a','b','c','d','c','d'])
));
/* 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'c', 'd', */
/* [ ] [ ] [ ] [ ] */
/* NOT [ ] [ ] [ ] [ ] [ ] [ ] */
assert(isEquals(
array(
array('number'=>2, 'values'=>array('a','b','a','b')),
array('number'=>1, 'values'=>array('c')),
array('number'=>1, 'values'=>array('d')),
),
splitToPatterns(['a','b','a','b','a','b','a','b','c','d'])
));
/* 'x', 'x', 'y', 'x', 'b', 'x', 'b', 'a' */
/* // [ ] [ ] [ ] [ ] [ ] [ ] */
assert(isEquals(
array(
array('number'=>2, 'values'=>array('x')),
array('number'=>1, 'values'=>array('y')),
array('number'=>2, 'values'=>array('x','b')),
array('number'=>1, 'values'=>array('a')),
),
splitToPatterns(['x','x','y','x','b','x','b','a'])
));
// one, two, one, two, one, two, one, two
// [ ] [ ]
assert(isEquals(
array(
array('number'=>2, 'values'=>array('one', 'two', 'one', 'two')),
),
splitToPatterns(['one', 'two', 'one', 'two', 'one', 'two', 'one', 'two'])
));
// 'one', 'two', 'one', 'two', 'three', 'four', 'one', 'two', 'three', 'four'
// [ ] [ ] [ ] [ ]
assert(isEquals(
array(
array('number'=>1, 'values'=>array('one')),
array('number'=>1, 'values'=>array('two')),
array('number'=>2, 'values'=>array('one','two','three','four')),
),
splitToPatterns(['one', 'two', 'one', 'two', 'three', 'four', 'one', 'two', 'three','four'])
));
/* 'a', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'c', */
/* [ ] [ ] [ ] [ ] */
assert(isEquals(
array(
array('number'=>1, 'values'=>array('a')),
array('number'=>2, 'values'=>array('a','b','a','b')),
array('number'=>1, 'values'=>array('c')),
),
splitToPatterns(['a','a','b','a','b','a','b','a','b','c'])
));
/* 'a', 'b', 'a', 'b', 'c', 'd', 'a', 'b', 'a', 'b', 'a', 'b' */
// [ ] [ ] [ ] [ ] [ ] [ ] [ ]
assert(isEquals(
array(
array('number'=>2, 'values'=>array('a', 'b')),
array('number'=>1, 'values'=>array('c')),
array('number'=>1, 'values'=>array('d')),
array('number'=>3, 'values'=>array('a','b')),
),
splitToPatterns(['a', 'b', 'a', 'b', 'c', 'd', 'a', 'b', 'a', 'b', 'a', 'b'])
));
/* 'a', 'c', 'd', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'c', */
/* [ ] [ ] [ ] [ ] [ ] [ ] */
assert(isEquals(
array(
array('number'=>1, 'values'=>array('a')),
array('number'=>2, 'values'=>array('a','b','a','b')),
array('number'=>1, 'values'=>array('c')),
),
splitToPatterns(['a','a','b','a','b','a','b','a','b','c'])
));