Given an array, find the minimum number of steps to make the array non decreasing. In one step any element of the array can be changed to any other number
Ex: 1 2 9 5 3 6
Ans: 2
Exp: Changing 9 to 2 and 3 to 5 will result in a non decreasing sequence: 1 2 2 5 5 6
Ex: 5 4 3 2
Ans: 3
What could be the brute-force and efficient approach to this problem?
Thanks in advance.