Counting Sort Basic Information
suggest changeCounting sort is an integer sorting algorithm for a collection of objects that sorts according to the keys of the objects.
Steps
- Construct a working array C that has size equal to the range of the input array A.
- Iterate through A, assigning C based on the number of times x appeared in A.
- Transform C into an array where C refers to the number of values ≤ x by iterating through the array, assigning to each C the sum of its prior value and all values in C that come before it.
- Iterate backwards through A, placing each value in to a new sorted array B at the index recorded in C. This is done for a given A by assigning B[C[A]] to A, and decrementing C[A] in case there were duplicate values in the original unsorted array.
Example of Counting Sort

Auxiliary Space: O(n+k)
Time Complexity: Worst-case: O(n+k)
, Best-case: O(n)
, Average-case O(n+k)
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