- Practice
- Algorithms
- Sorting
- Counting Sort 1

# Counting Sort 1

# Counting Sort 1

**Comparison Sorting**

Quicksort usually has a running time of , but is there an algorithm that can sort even faster? In general, this is not possible. Most sorting algorithms are *comparison sorts*, i.e. they sort a list just by comparing the elements to one another. A comparison sort algorithm cannot beat (worst-case) running time, since represents the minimum number of comparisons needed to know where to place each element. For more details, you can see these notes (PDF).

**Alternative Sorting**

Another sorting method, the *counting sort*, does not require comparison. Instead, you create an integer array whose index range covers the entire range of values in your array to sort. Each time a value occurs in the original array, you increment the counter at that index. At the end, run through your counting array, printing the value of each non-zero valued index that number of times.

**Example**

All of the values are in the range , so create an array of zeros, . The results of each iteration follow:

```
i arr[i] result
0 1 [0, 1, 0, 0]
1 1 [0, 2, 0, 0]
2 3 [0, 2, 0, 1]
3 2 [0, 2, 1, 1]
4 1 [0, 3, 1, 1]
```

The frequency array is . These values can be used to create the sorted array as well: .

**Note**

For this exercise, always return a frequency array with 100 elements. The example above shows only the first 4 elements, the remainder being zeros.

**Challenge**

Given a list of integers, count and return the number of times each value appears as an array of integers.

**Function Description**

Complete the *countingSort* function in the editor below.

countingSort has the following parameter(s):

*arr[n]:*an array of integers

**Returns**

*int[100]:*a frequency array

**Input Format**

The first line contains an integer , the number of items in .

Each of the next lines contains an integer where .

**Constraints**

^{}

**Sample Input**

```
100
63 25 73 1 98 73 56 84 86 57 16 83 8 25 81 56 9 53 98 67 99 12 83 89 80 91 39 86 76 85 74 39 25 90 59 10 94 32 44 3 89 30 27 79 46 96 27 32 18 21 92 69 81 40 40 34 68 78 24 87 42 69 23 41 78 22 6 90 99 89 50 30 20 1 43 3 70 95 33 46 44 9 69 48 33 60 65 16 82 67 61 32 21 79 75 75 13 87 70 33
```

**Sample Output**

```
0 2 0 2 0 0 1 0 1 2 1 0 1 1 0 0 2 0 1 0 1 2 1 1 1 3 0 2 0 0 2 0 3 3 1 0 0 0 0 2 2 1 1 1 2 0 2 0 1 0 1 0 0 1 0 0 2 1 0 1 1 1 0 1 0 1 0 2 1 3 2 0 0 2 1 2 1 0 2 2 1 2 1 2 1 1 2 2 0 3 2 1 1 0 1 1 1 0 2 2
```

**Explanation**

Each of the resulting values represents the number of times appeared in .