Frequency Counter Pattern Using Hash Map in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a hash map for counting frequencies.

DSA C

int [1][256] = {0};

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Amap

Bcount

Cfreq

Dfrequency

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that is too long or unclear.

Not initializing the array to zero.

The variable freq is commonly used to store frequency counts in an array representing ASCII characters.

2fill in blank

medium

Complete the code to increase the frequency count of a character in the string.

DSA C

freq[(unsigned char)str[i]][1];

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A++

B--

C+=

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using -- which decreases the count.

Using = which overwrites the count.

The ++ operator increases the count by 1 for the character at position i.

3fill in blank

hard

Fix the error in the condition to check if a character appears more than once.

DSA C

if (freq[(unsigned char)str[i]] [1] 1) {

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A<=

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using == which only checks for exactly one occurrence.

Using <= or < which check for less or equal.

The condition freq[...] > 1 checks if the character appears more than once.

4fill in blank

hard

Fill both blanks to complete the loop that counts character frequencies in a string.

DSA C

for (int [1] = 0; [2] < length; [2]++) {
    freq[(unsigned char)str[i]]++;
}

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Ai

Bj

Clength

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variables in the loop condition and increment.

Using a variable not declared in the loop.

The variable i is used as the loop counter to access each character in the string.

5fill in blank

hard

Fill all three blanks to create a frequency counter that prints characters appearing more than once.

DSA C

for (int [1] = 0; [1] < 256; [1]++) {
    if (freq[[1]] [2] 1) {
        printf("%c appears %d times\n", (char)[1], freq[[1]]);
    }
}

Drag options to blanks, or click blank then click option'

Ai

B>

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variables in the loop and inside the if condition.

Using the wrong comparison operator in the if condition.

The loop variable i iterates over all possible characters. The condition freq[i] > 1 checks for characters appearing more than once. The variable i is used to print the character.