DATA STRUCTURES PROGRAM • HEAPS, HASHING & DISJOINT SETS

Count Frequencies with a Hash-Style Table

Learn how to count frequencies with a hash-style table using a clear C program.

IntermediateFrequency tableDirect addressingCounting

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

2 occurs 2 time(s)
3 occurs 1 time(s)
4 occurs 3 time(s)

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    int values[] = {4, 2, 4, 3, 2, 4};
    int frequency[11] = {0};
    for (int index = 0; index < 6; index++) frequency[values[index]]++;
    for (int value = 0; value <= 10; value++)
        if (frequency[value] > 0) printf("%d occurs %d time(s)\n", value, frequency[value]);
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

2 occurs 2 time(s)
3 occurs 1 time(s)
4 occurs 3 time(s)

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Use each bounded integer as an array index and increment its counter.
Display the computed result.

Use each bounded integer as an array index and increment its counter.

EFFICIENCY

Time and space complexity

Time complexity

O(n + range)

Auxiliary space

O(n)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

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Initialize variables before using their values.

Check this

Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.