2. What is Radix?
■ Radix means “The base of a system of numeration.”
■ In Computer Science Radix Sort is a non- comparative integer sorting algorithm
that sort data with integer keys by sorting grouping keys by individual digits which
share same significant position and value.
■ The Radix Sort algorithm is an important sorting algorithm that is integral to suffix
-array construction algorithms. It is also useful on parallel machines.
3. What is Radix?
■ Radix is a term used to describe the number of digits utilized in a positional
number system before "rolling over" to the next digit's place
■ Radix sort was developed for sorting large integers, but it treats an integer as a
string of digits, so it is really a string sorting algorithm
4. Two Types of Radix Sorting
■ MSD(Most significant digit)
■ LSD(Least significant digit)
5. MSD(Most significant digit)
■ An MSD radix sort starts processing the keys from the most significant digit,
leftmost digit, to the least significant digit, rightmost digit.
■ A most significant digit (MSD) radix sort can be used to sort keys in lexicographic
order.
■ Unlike a least significant digit (LSD) radix sort, a most significant digit radix
sort does not necessarily preserve the original order of duplicate keys.
6. LSD(Least significant digit)
■ LSD radix sorts have resurfaced as an alternative to high performance comparison-
based sorting algorithms (like heapsort and merge sort) that require O(n · log n)
comparisons, where n is the number of items to be sorted.
■ A Least significant digit (LSD) Radix sort is a fast stable sorting algorithm which
can be used to sort keys in integer representation order.
■ Keys may be a string of characters, or numerical digits in a given 'radix'.
7. Advantages
■ Fast when the keys are short i.e. when the range of the array elements is less.
■ Used in suffix array construction algorithms like Manber's algorithm and DC3
algorithm.
8. Disadvantages
■ Since Radix Sort depends on digits or letters, Radix Sort is much less flexible than
other sorts. Hence , for every different type of data it needs to be rewritten.
■ The constant for Radix sort is greater compared to other sorting algorithms.
■ It takes more space compared to Quicksort which is in place sorting.
9. Radix Sort - step by step guide
We have unsorted numbers and our task is to sort them in ascending order
Since all of them have 2 digits so, the sorting process will require 2 pass.
12 18 11 60 15 80 25 50
10. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
12 has 2 in the 1st place so we will put it in Q2.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
12
11. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
18 has 8 in the 1st place so we will put it in Q8.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
12 18
12. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
11 has 1 in the 1st place so we will put it in Q1.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
11 12 18
13. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
60 has 0 in the 1st place so we will put it in Q0.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60 11 12 18
14. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
15 has 5 in the 1st place so we will put it in Q5.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60 11 12 15 18
15. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
80 has 0 in the 1st place so we will put it in Q0.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60
80
11 12 15 18
16. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
25 has 5 in the 1st place so we will put it in Q5.
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60
80
11 12 15
25
18
17. Radix Sort - step by step guide
Based on the algorithm, sort the array according to the one’s digit (Leased Significant
Digit)
Sort the number using 1st digit from right.
50 has 0 in the 1st place so we will put it in Q0.
Pass 1 is complete
12 18 11 60 15 80 25 50
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60
80
50
11 12 15
25
18
18. Radix Sort - step by step guide
Take the numbers out from the box 0 to 9 from top
Pass 2
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
60 has 6 in the 2nd place so we will put it in Q6.
60 80 50 11 12 15 25 18
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60
19. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
80 has 8 in the 2nd place so we will put it in Q8.
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
60 80
20. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
50 has 5 in the 2nd place so we will put it in Q5.
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
50 60 80
21. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
11 has 1 in the 2nd place so we will put it in Q1.
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
11 50 60 80
22. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
12 has 1 in the 2nd place so we will put it in Q1.
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
11
12
50 60 80
23. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
15 has 1 in the 2nd place so we will put it in Q1.
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
11
12
15
50 60 80
24. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
25 has 2 in the 2nd place so we will put it in Q2.
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
11
12
15
25 50 60 80
25. Radix Sort - step by step guide
Now, sort the array according to most significant digit (MSD)
Sort the numbers using 2nd digit from right.
18 has 1 in the 2nd place so we will put it in Q1.
Pass 2 is complete
60 80 50 11 12 15 25 18
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
11
12
15
18
25 50 60 80
26. Radix Sort - step by step guide
Take the numbers out from the box 0 to 9 from top
Since, we have completed pass 2 so we will stop here.
So, the numbers are sorted in ascending order.
11 12 15 18 25 50 60 80
