C PROGRAMMING PROGRAM • FUNCTIONS & RECURSION

Calculate Power Using Recursion

Learn how to calculate power using recursion using a clear C program.

IntermediateRecursionExponentiation by squaringDivide and conquer

PROBLEM UNDERSTANDING

Input and expected output

Sample input

3 5

Sample output

Result = 243

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

long long power(long long base, unsigned int exponent)
{
    if (exponent == 0) return 1;
    long long half = power(base, exponent / 2);
    if (exponent % 2 == 0) return half * half;
    return base * half * half;
}

int main(void)
{
    long long base;
    unsigned int exponent;

    printf("Enter integer base and non-negative exponent: ");
    scanf("%lld %u", &base, &exponent);
    printf("Result = %lld\n", power(base, exponent));
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

Result = 243

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Recursively compute half the exponent and square it, multiplying by the base only for odd exponents.
Display the computed result.

Recursively compute half the exponent and square it, multiplying by the base only for odd exponents.

EFFICIENCY

Time and space complexity

Time complexity

O(log n)

Auxiliary space

O(log 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.