Exercise 2-1: Programming in C is fun!

This task requires printing a specific string to the console.

#include <stdio.h>

int main() {
    printf("Programming in C is fun!");
    return 0;
}

Exercise 2-3: Output Inverted Triangle Pattern

Prints an inverted triangle pattern using asterisks and spaces with specific alignment.

#include <stdio.h>

int main() {
    printf("* * * *\n");
    printf(" * * *\n");
    printf("  * *\n");
    printf("   *");
    return 0;
}

Exercise 2-4: Temperature Conversion

Converts a fixed Fahrenheit value (150) to Celsius using the standard conversion formula.

#include <stdio.h>

int main() {
    int f_temp = 150;
    int c_temp;
    c_temp = 5 * (f_temp - 32) / 9;
    printf("fahr = %d, celsius = %d", f_temp, c_temp);
    return 0;
}

Exercise 2-6: Calculate Free Fall Distance

Calculates the distance an object falls in 3 seconds given gravity is 10 m/s².

#include <stdio.h>

int main() {
    double time = 3.0;
    double gravity = 10.0;
    double distance = 0.5 * gravity * time * time;
    printf("height = %.2f", distance);
    return 0;
}

Exercise 2-8: Calculate Celsius Temperature

Reads an integer Fahrenheit value from input and converts it to Celsius.

#include <stdio.h>

int main() {
    int f_val, c_val;
    scanf("%d", &f_val);
    c_val = 5 * (f_val - 32) / 9;
    printf("Celsius = %d", c_val);
    return 0;
}

Exercise 2-9: Integer Arithmetic Operations

Performs addition, subtraction, multiplication, and division on two integers.

#include <stdio.h>

int main() {
    int num1, num2;
    scanf("%d %d", &num1, &num2);
    printf("%d + %d = %d\n", num1, num2, num1 + num2);
    printf("%d - %d = %d\n", num1, num2, num1 - num2);
    printf("%d * %d = %d\n", num1, num2, num1 * num2);
    printf("%d / %d = %d\n", num1, num2, num1 / num2);
    return 0;
}

Exercise 2-10: Calculate Piecewise Function 1

Computes a function where $f(x) = 1/x$ if $x \neq 0$, otherwise $f(x) = 0$.

#include <stdio.h>

int main() {
    double x, y;
    scanf("%lf", &x);
    if (x != 0) {
        y = 1.0 / x;
    } else {
        y = 0.0;
    }
    printf("f(%.1f) = %.1f", x, y);
    return 0;
}

Exercise 2-11: Calculate Piecewise Function 2

Computes a function involving square root for non-negative inputs and a polynomial expression for negative inputs.

#include <stdio.h>
#include <math.h>

int main() {
    double x, res;
    scanf("%lf", &x);
    if (x >= 0) {
        res = sqrt(x);
    } else {
        res = pow(x + 1, 2) + 2 * x + 1.0 / x;
    }
    printf("f(%.2f) = %.2f", x, res);
    return 0;
}

Exercise 2-12: Output Fahrenheit-Celsius Conversion Table

Generates a conversion table within a valid range, stepping by 2 degrees.

#include <stdio.h>

int main() {
    int low, high;
    double celsius;
    scanf("%d %d", &low, &high);

    if (low > high || high > 100 || low <= 0) {
        printf("Invalid.");
    } else {
        printf("fahr celsius\n");
        for (int f = low; f <= high; f += 2) {
            celsius = 5.0 * (f - 32)0 / 9.0;
            printf("%d%6.1f\n", f, celsius);
        }
    }
    return 0;
}

Exercise 2-13: Sum of Nth Reciprocals

Calculates the sum of the series $1 + 1/2 + ... + 1/n$.

#include <stdio.h>

int main() {
    int n, i;
    double total = 0.0;
    scanf("%d", &n);
    for (i = 1; i <= n; i++) {
        total += 1.0 / i;
    }
    printf("sum = %lf", total);
    return 0;
}

Exercise 2-14: Sum of Odd Reciprocals

Calculates the sum of reciprocals of the first N odd numbers.

#include <stdio.h>

int main() {
    int count, i;
    double sum = 0.0;
    scanf("%d", &count);
    for (i = 1; i <= count; i++) {
        sum += 1.0 / (2 * i - 1);
    }
    printf("sum = %lf", sum);
    return 0;
}

Exercise 2-15: Sum of Simple Alternating Series

Calculates the sum of a series with alternating signs: $1 - 1/4 + 1/7 - 1/10 + ...$.

#include <stdio.h>

int main() {
    int n, i;
    int sign = 1;
    double sum = 0.0;
    scanf("%d", &n);
    for (i = 1; i <= n; i++) {
        sum += 1.0 / (sign * (3 * i - 2));
        sign = -sign;
    }
    printf("sum = %.3lf", sum);
    return 0;
}

Exercise 2-17: Generate Powers of 3 Table

Prints values of 3 raised to the power of 0 to n.

#include <stdio.h>
#include <math.h>

int main() {
    int n, i;
    long long val;
    scanf("%d", &n);
    for (i = 0; i <= n; i++) {
        val = (long long)pow(3, i);
        printf("pow(3,%d) = %lld\n", i, val);
    }
    return 0;
}

Exercise 2-18: Calculate Combination Number

Calculates the combination number $C(n, m)$ using factorials.

#include <stdio.h>

double getFactorial(int num);

int main() {
    int m, n;
    double result;
    scanf("%d %d", &m, &n);
    result = getFactorial(n) / (getFactorial(m) * getFactorial(n - m));
    printf("result = %.0lf", result);
    return 0;
}

double getFactorial(int num) {
    double product = 1.0;
    for (int i = 1; i <= num; i++) {
        product *= i;
    }
    return product;
}

Problem 2-1: Find Integer Mean

Calculates the sum and average of four integers.

#include <stdio.h>

int main() {
    int a, b, c, d;
    int sum;
    double avg;
    scanf("%d %d %d %d", &a, &b, &c, &d);
    sum = a + b + c + d;
    avg = sum / 4.0;
    printf("Sum = %d; Average = %.1f", sum, avg);
    return 0;
}

Problem 2-2: Tiered Electricity Pricing

Calculates electricity cost based on usage with different rates for usage above and below 50 kWh.

#include <stdio.h>

int main() {
    int usage;
    double cost = 0.0;
    scanf("%d", &usage);
    
    if (usage >= 0 && usage <= 50) {
        cost = usage * 0.53;
    } else if (usage > 50) {
        cost = 50 * 0.53 + (usage - 50) * 0.58;
    } else {
        printf("Invalid Value!");
        return 0;
    }
    printf("cost = %.2lf", cost);
    return 0;
}

Problem 2-3: Partial Sum of Squares and Reciprocals

Calculates the sum of squares plus reciprocals for a range of integers.

#include <stdio.h>
#include <math.h>

int main() {
    int start, end, i;
    double total = 0.0;
    scanf("%d %d", &start, &end);
    for (i = start; i <= end; i++) {
        total += pow(i, 2) + 1.0 / i;
    }
    printf("sum = %lf", total);
    return 0;
}

Problem 2-4: Sum of Alternating Sequence

Calculates the sum of an alternating sequence: $1 - 2/3 + 3/5 - 4/7 + ...$ up to N terms.

#include <stdio.h>

int main() {
    int n, i;
    int sign = 1;
    double sum = 0.0;
    scanf("%d", &n);
    for (i = 1; i <= n; i++) {
        sum += sign * i / (2.0 * i - 1);
        sign = -sign;
    }
    printf("%.3lf", sum);
    return 0;
}

Problem 2-5: Sum of Square Root Sequence

Calculates the sum of square roots of integers from 1 to N.

#include <stdio.h>
#include <math.h>

int main() {
    int limit, i;
    double sum = 0.0;
    scanf("%d", &limit);
    for (i = 1; i <= limit; i++) {
        sum += sqrt(i);
    }
    printf("sum = %.2lf", sum);
    return 0;
}

Problem 2-6: Sum of Factorial Sequence

Calculates the sum of factorials from $1!$ to $N!$.

#include <stdio.h>

long long computeFactorial(int n);

int main() {
    int n, i;
    long long total = 0;
    scanf("%d", &n);
    for (i = 1; i <= n; i++) {
        total += computeFactorial(i);
    }
    printf("%lld", total);
    return 0;
}

long long computeFactorial(int n) {
    long long res = 1;
    for (int i = 1; i <= n; i++) {
        res *= i;
    }
    return res;
}