ADVANCED DATA STRUCTURES PROGRAM • LEVEL 8 — PERFORMANCE ANALYSIS

Measure Recursive Fibonacci Calls

Learn how to measure recursive fibonacci calls using a clear C program.

IntermediateOperation countingAsymptotic analysis

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

Fibonacci = 5 Calls = 15

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int fibonacci(int number, int *calls)
{
    (*calls)++;
    if (number < 2) return number;
    return fibonacci(number - 1, calls) + fibonacci(number - 2, calls);
}

int main(void)
{
    int calls = 0;
    int value = fibonacci(5, &calls);
    printf("Fibonacci = %d Calls = %d\n", value, calls);
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

Fibonacci = 5 Calls = 15

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Count every recursive activation to expose the repeated work in naive Fibonacci.
Display the computed result.

Count every recursive activation to expose the repeated work in naive Fibonacci.

EFFICIENCY

Time and space complexity

Time complexity

O(2^n)

Auxiliary space

O(n)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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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.