Counting Sort Algorithm in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the count array with the correct size.

DSA C++

int count[[1] + 1] = {0};

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Asum

Bmin_val

Cn

Dmax_val

Attempts:

3 left

💡 Hint

Common Mistakes

Using the size of the input array instead of the maximum value.

Using minimum value for size.

The count array size should be based on the maximum value in the input array to cover all possible values.

2fill in blank

medium

Complete the code to increment the count of the current element.

DSA C++

count[arr[i]][1];

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A++

B--

C+=

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using decrement operator instead of increment.

Assigning instead of incrementing.

We increment the count for the element at arr[i] by 1 to record its frequency.

3fill in blank

hard

Fix the error in updating the count array to hold cumulative counts.

DSA C++

for (int i = 1; i <= [1]; i++) {
    count[i] = count[i] [2] count[i - 1];
}

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A+

B-

C*

Dmax_val

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction instead of addition.

Using multiplication or division which is incorrect.

The cumulative count is calculated by adding the previous count to the current count.

4fill in blank

hard

Fill both blanks to place elements in the output array in correct order.

DSA C++

output[count[arr[i]] [1]] = arr[i];
count[arr[i]] [2];

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A- 1

B+ 1

C--

D++

Attempts:

3 left

💡 Hint

Common Mistakes

Not subtracting 1 causing off-by-one errors.

Incrementing count instead of decrementing.

The position is count[arr[i]] - 1 because arrays are zero-indexed, and then we decrement the count for the next occurrence.

5fill in blank

hard

Fill all three blanks to copy the sorted output back to the original array.

DSA C++

for (int i = 0; i < [1]; i++) {
    arr[i] = [2][[3]];
}

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An

Boutput

Ci

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong array names.

Using wrong index variables.

We copy each element from the output array back to the original array using the loop index.