For example we have the array like this:
[, , , , , ]
First step is using Counting sort for last digit, in our example is:
[53, 89, 150, 36, 633, 233]
[, , , , , ]
Then sort according to the last digit:
[, , , , , ]
Then using second last digit to the sort:
[, , , , , ]
Last using the last digist to do the sort, and using '0' if missing the digit:
[, , , , , ]
The whole array should be sorted.
Time complexiity:
n = 6: array length is 6
d = 3: max digit for number is 3
b = 10, we use 10 based counting [0, 1,2,3...9]
For each step it takes O(n+b) to do the sorting
Then for the whole algorithm is O(d * (n+b))