Quiz 58: Make the sequence increasing

Problem:

Given a sequence, you have to make the sequence increasing by adding a number d any number of times. like if d is 2 and sequence is 5 1, then adding 2 for 3 times will make sequence 5 7 which is in increasing order. Number of moves for this example was 3. Find minimum number of moves required to make the sequence increasing.

Input Format: 

N D(total numbers and number D to be added)

sequence(each number separated by space)

Output Format: 

Minimum number of moves

Constraints: 

None

Sample Input

6 3
1 5 2 22 21 2

Sample Output:

11

Explanations:

new sequence would be 1,5,8(2+3*2),22,24(21+3*1),26(2+3*8), so total=2+1+8=11

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Solution:

chomp($line1=<STDIN>);
($n,$d)=split(" ",$line1);

chomp($line2=<STDIN>);
@arr=split(" ",$line2);
$ans=0;
for($i=0;$i<$n-1;$i++)
{
if($arr[$i]>=$arr[$i+1])
{
$dif=$arr[$i]-$arr[$i+1];
$num=int($dif/$d)+1;
$ans=$ans+$num;
$arr[$i+1]=$arr[$i+1]+($num*$d);
}
}
print $ans;

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Tips:

Update array elements and continue comparing