两个蛋拼图未定义偏移在PHP中

Question

I have translated this code from java to php but it yields this error:

undefined offset

I have tried a lot of possibilities but can't solve it.

function calculate($bulbs,  $floors){

  //$T[][] = new int[$eggs+1][$floors+1];

  $T=array();
  $c=0;
  for ( $i=0; $i <= $floors; $i++ ) {
    $T[1][$i] = $i;
  }
  for ( $e = 2; $e <= $bulbs; $e++ ) {
    for ( $f = 1; $f <=$floors; $f++ ) {
      $T[$e][$f] = PHP_INT_MAX;
      for ( $k = 1; $k <=$f ; $k++ ) {
        $c = 1 + max( $T[$e-1][$k-1], $T[$e][$f-$k] );
        if ( $c < $T[$e][$f] ) {
          $T[$e][$f] = $c;
        }
      }
    }
  }
  return $T[$bulbs][$floors];
}
echo calculate(2,100);

But my answer is coming right, which is 14 in this example.

Answer 1

The Issue:

The error is this line:

    $c = 1 + max($T[$e-1][$k-1], $T[$e][$f-$k]);

It happens when $f is equal to $k, because it is accessing $T[$e][0], which hasn't been set (given we set $T[$e][$f] = PHP_INT_MAX; and $f starts at 1).

Possible solution:

One could use array_key_exists() to check if the element exists:

if (array_key_exists($f - $k, $T[$e])) {
    $c = 1 + max($T[$e-1][$k-1], $T[$e][$f-$k]);
}
else {
    $c = 1 + $T[$e-1][$k-1];
}