F - To Add Which?

Description

    There is an integer sequence with N integers. You can use 1 unit of cost to increase any integer in the sequence by 1.
    Could you tell us the least units of cost to achieve that, the absolute value of difference between any two adjacent integers is not more than D?

Input

    The first line has one integer T, means there are T test cases.
    For each test case, the first line has two integers N, D (1 <= N <= 10⁵, 0 <= D < 10⁹), which have the same meaning as above. The next line has N integers describing the sequence. Every integer in this sequence is in range [0, 10⁹).
    The size of the input file will not exceed 5MB.

Output

    For each test case, print an integer in one line, indicates the desired answer.

Sample Input

3
5 2
1 3 5 3 5
5 1
1 2 3 5 6
5 2
1 7 3 5 9

Sample Output

0
3
8

数据比较水，n^2也能过，有nlogn的算法，要用线段树和递归，暂时不会写。。。

#include<stdio.h>
#include<math.h>
long long a[100005];
int main()
{
	int T,i,j;
	long long n,m,sum;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%lld%lld",&n,&m);
		sum=0;
		for(i=1;i<=n;i++)
		{
			scanf("%lld",&a[i]);
		}
		for(i=2;i<=n;i++)
		{
           if(fabs(a[i]-a[i-1])<=m )
		   continue;
		   else if(a[i]<a[i-1])
		   {
   			  sum=sum+a[i-1]-m-a[i];
   			  a[i]=a[i-1]-m;
	       }
	       else if(a[i]>a[i-1])
	       {
       		  sum=sum+a[i]-m-a[i-1];
       		  a[i-1]=a[i]-m;
       		  for(j=i-1;j>=2;j--)
       		  {
  		       	 if(fabs(a[j]-a[j-1])<=m )
  		       	 break;
  		       	 if(a[j]>a[j-1])
  		       	 {
 	       		   sum=sum+a[j]-m-a[j-1];
	   	           a[j-1]=a[j]-m;
   		         }
	           }
   	        }
         }
		printf("%lld\n",sum);
	}
}