Area of Shapes - Problem

You are given three different shapes and need to calculate their areas based on the provided dimensions:

Circle: Given radius r, calculate area using formula π × r²
Rectangle: Given length l and width w, calculate area using formula l × w
Triangle: Given base b and height h, calculate area using formula ½ × b × h

The program should read the shape type and its dimensions, then output the calculated area rounded to 2 decimal places.

Note: Use π = 3.14159 for circle calculations.

Input & Output

Example 1 — Circle Area

$ Input: shape = "circle", dimensions = [5]

› Output: 78.54

💡 Note: Circle area = π × r² = 3.14159 × 5² = 3.14159 × 25 = 78.54 square units

Example 2 — Rectangle Area

$ Input: shape = "rectangle", dimensions = [6, 4]

› Output: 24.00

💡 Note: Rectangle area = length × width = 6 × 4 = 24.00 square units

Example 3 — Triangle Area

$ Input: shape = "triangle", dimensions = [8, 3]

› Output: 12.00

💡 Note: Triangle area = ½ × base × height = 0.5 × 8 × 3 = 12.00 square units

Constraints

Shape will be one of: "circle", "rectangle", "triangle"
Dimensions array will have appropriate length for each shape
All dimension values will be positive numbers
Results should be rounded to 2 decimal places

Visualization

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Asked in

G Google 15 a Amazon 12 M Microsoft 10

The key insight is applying the correct mathematical formula based on shape type: π×r² for circles, l×w for rectangles, and ½×b×h for triangles. Best approach uses direct conditional logic. Time: O(1), Space: O(1)

Common Approaches

✓ Direct Formula Application

⏱️ Time: O(1) Space: O(1)

Read the shape type and dimensions, then apply the appropriate area formula. Use conditional logic to determine which formula to use based on the shape parameter.

Formula Lookup Table

⏱️ Time: O(1) Space: O(1)

Instead of multiple if-else statements, create a more maintainable structure that separates the formula logic. This approach is more extensible for adding new shapes.

Direct Formula Application — Algorithm Steps

Check the shape type (circle, rectangle, or triangle)
Apply the corresponding mathematical formula
Round the result to 2 decimal places

Visualization

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Step-by-Step Walkthrough

Identify Shape

Read shape type and select appropriate formula

Apply Formula

Use mathematical formula with given dimensions

Round Result

Round calculated area to 2 decimal places

Code -

solution.c — C

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

double solution(char* shape, double* dimensions, int dimCount) {
    double area = 0.0;
    
    if (strcmp(shape, "circle") == 0) {
        double r = dimensions[0];
        area = 3.14159 * r * r;
    } else if (strcmp(shape, "rectangle") == 0) {
        double l = dimensions[0];
        double w = dimensions[1];
        area = l * w;
    } else if (strcmp(shape, "triangle") == 0) {
        double b = dimensions[0];
        double h = dimensions[1];
        area = 0.5 * b * h;
    }
    
    return round(area * 100.0) / 100.0;
}

int main() {
    char shape[20];
    fgets(shape, sizeof(shape), stdin);
    shape[strcspn(shape, "\n")] = 0; // Remove newline
    
    char dimLine[100];
    fgets(dimLine, sizeof(dimLine), stdin);
    
    // Parse JSON array manually
    double dimensions[10];
    int dimCount = 0;
    char* token = strtok(dimLine, "[],");
    
    while (token != NULL) {
        dimensions[dimCount++] = atof(token);
        token = strtok(NULL, "[],");
    }
    
    double result = solution(shape, dimensions, dimCount);
    printf("%.2f\n", result);
    
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(1)

Constant time operations - just arithmetic calculations

✓ Linear Growth

Space Complexity

O(1)

Only storing a few variables for dimensions and result

✓ Linear Space

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Area of Shapes - Problem

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Direct Formula Application — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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