Abstract Shapes

Lab C++ Intermediate 20 points

Write an abstract class Shape with pure virtual area() and name(). Implement Circle, Rect and Triangle. Read shapes into a vector<unique_ptr<Shape>>, print each name area (2 decimals) and the total.

Input

n, then lines circle r, rect w h, triangle b h.

Output

n + 1 lines.

Example

Input

3
circle 1
rect 2 3
triangle 4 5

Output

circle 3.14
rect 6.00
triangle 10.00
total 19.14

Sample input available Sample output available

Editor

C++

Hints

= 0 makes a function pure virtual; the class becomes abstract.

Solution explanation

The loop works with any shape through the base-class interface.

Show solution

#include <iostream>
#include <iomanip>
#include <memory>
#include <string>
#include <vector>
#include <cmath>
using namespace std;

class Shape {
public:
    virtual ~Shape() = default;
    virtual double area() const = 0;
    virtual string name() const = 0;
};

class Circle : public Shape {
public:
    explicit Circle(double r) : r_(r) {}
    double area() const override { return M_PI * r_ * r_; }
    string name() const override { return "circle"; }
private:
    double r_;
};

class Rect : public Shape {
public:
    Rect(double w, double h) : w_(w), h_(h) {}
    double area() const override { return w_ * h_; }
    string name() const override { return "rect"; }
private:
    double w_, h_;
};

class Triangle : public Shape {
public:
    Triangle(double b, double h) : b_(b), h_(h) {}
    double area() const override { return b_ * h_ / 2; }
    string name() const override { return "triangle"; }
private:
    double b_, h_;
};

int main() {
    int n;
    cin >> n;
    vector<unique_ptr<Shape>> shapes;
    for (int i = 0; i < n; i++) {
        string kind;
        cin >> kind;
        if (kind == "circle") {
            double r; cin >> r;
            shapes.push_back(make_unique<Circle>(r));
        } else if (kind == "rect") {
            double w, h; cin >> w >> h;
            shapes.push_back(make_unique<Rect>(w, h));
        } else {
            double b, h; cin >> b >> h;
            shapes.push_back(make_unique<Triangle>(b, h));
        }
    }
    double total = 0;
    cout << fixed << setprecision(2);
    for (const auto &s : shapes) {
        cout << s->name() << " " << s->area() << "\n";
        total += s->area();
    }
    cout << "total " << total << "\n";
    return 0;
}

Output

Answer