Max sum i*arr[i]

Max sum i*arr[i]

  October 23, 2017    

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Idea is to first find sum of array .
Calculate default max sum.
Exclude i-1th element by removing it from sum and subtract this value from max sum and include i-1th element * (n-1 )
As we are rotating element that's why removing it and including with multiplied by n-1.


Code:

 int max_sum(int A[], int n)
    {
int sum=A[0];
int max_sum=0;
for(int i=1;i<n;++i)
{ sum+=A[i];
    max_sum+=(i)*A[i];
}
int res=max_sum;
for(int i=1;i<n;++i)
{
    max_sum=max_sum-(sum-A[i-1])+A[i-1]*(n-1);
    res=Math.max(res,max_sum);
}
return res;
    }