Hi Everyone! I have asked this question on stackexchange and got no chance getting an answer to my problem. Will you plz help me solve it?

I have come up with a solution but I don't exactly know if it is true. I think for the tallest possible height, we can always get to that by adding d to the highest tower. and for the lowest possible height, we can get the min of the array and add 1 to its m neighboring towers in a for loop and keep doing this again. finally the tallest tower will have the minimum height. Am I correct?