我在 C++ 和 PHP 上有两个相同的双向合并排序示例。C++ 示例工作正常,但 PHP 没有。
为什么php示例不起作用?找不到错误:
function merge($m, $low, $mid, $high)
{
$i = $low;
$j = $mid+1;
$k = 0;
$tmp = array();
while (($i <= $mid) && ($j <= $high))
{
if ($m[$i] > $m[$j])
$tmp[$k++] = $m[$i++];
else
$tmp[$k++] = $m[$j++];
}
if ($i <= $mid)
{
while ($i <= $mid)
$tmp[$k++] = $m[$i++];
}
if ($j <= $high)
{
while ($j <= $high)
$tmp[$k++] = $m[$j++];
}
for ($i = $low; $i <= $high; $i++)
$m[$i] = $tmp[$i-$low];
return $m;
}
function mergeSort($m, $low, $high)
{
if ($high > $low)
{
$middle = ($high+$low)/2;
mergeSort($m, $low, $middle);
mergeSort($m, $middle+1, $high);
merge($m, $low, $middle, $high);
}
}
$m = array(0,3,2,4);
$m = mergeSort($m, 0, 3);
echo $m[0]; // there null :(
C++ 示例,它的工作正常:
int m[10];
void merge(int low, int mid, int high)
{
int i = low;
int j = mid+1;
int z = 0;
int tmp[10] = {0};
while ((i <= mid) && (j <= high))
{
if (m[i] < m[j])
tmp[z++] = m[i++];
else
tmp[z++] = m[j++];
}
if (i <= mid)
{
while (i <= mid)
tmp[z++] = m[i++];
}
if (j <= high)
{
while (j <= high)
tmp[z++] = m[j++];
}
for (int a = low; a <= high; a++)
m[a] = tmp[a-low];
}
void mergeSort(int low, int high)
{
if (low < high)
{
int middle = (high+low)/2;
mergeSort(low, middle);
mergeSort(middle+1, high);
merge(low, middle, high);
}
return;
}
int main(array<System::String ^> ^args)
{
for (int i = 0; i < 10; i++)
m[i] = rand()%101;
mergeSort(0, 7);
for (int i = 0; i < 10; i++)
Console::WriteLine("{0}", m[i]);
Console::ReadLine();
return 0;
}
我猜,有递归循环,因为页面加载时间过长。但不知道如何检查它。我做错了什么?