Increment to Top

Create a function that returns the total number of steps it takes to transform each element to the maximal element in the list. Each step consists of incrementing a digit by one.

Examples

increment_to_top([3, 4, 5]) ➞ 3
# Maximal element in the array is 5.
# To transform 3 to 5 requires 2 steps: 3 -> 4, 4 -> 5.
# To transform 4 to 5 requires 1 step: 4 -> 5.
# Total steps required is 3.

increment_to_top([4, 3, 4]) ➞ 1
# Maximal element in the array is 4.
# To transform 3 to 4 requires 1 steps: 3 -> 4.
# Total steps required is 1.

increment_to_top([3, 3, 3]) ➞ 0

increment_to_top([3, 10, 3]) ➞ 14

Notes

• If the list contains only the same digits, return 0 (see example #3).
• Bonus: Can you write a solution that achieves this by only traversing the list once? (i.e. without finding the max beforehand)