/*
 * Author: Amit Dutta (amitdutta4255@gmail.com)
 * Repo: https://github.com/notamitgamer/bsc
 * License: MIT
 */
/* Write a program to implement a Diagonal Matrix a Lower Triangular Matrix, an Upper Triangular Matrix, and a
Symmetric Matrix using a one-dimensional array. */

#include <iostream>

using namespace std;

class Matrix
{
private:
  int n, *arr;

public:
  Matrix(int size)
  {
    n = size;
    arr = new int[n * (n + 1) / 2];
  }

  void setDiagonal(int i, int j, int x)
  {
    if (i == j)
      arr[i] = x;
  }
  void setLowerTri(int i, int j, int x)
  {
    if (i >= j)
      arr[i * (i + 1) / 2 + j] = x;
  }
  void setUpperTri(int i, int j, int x)
  {
    if (i <= j)
      arr[n * i - (i * (i - 1) / 2) + (j - i)] = x;
  }
  void setSymmetric(int i, int j, int x)
  {
    (i >= j) ? arr[i * (i + 1) / 2 + j] = x : arr[j * (j + 1) / 2 + i] = x;
  }

  int getDiagonal(int i, int j)
  {
    return (i == j) ? arr[i] : 0;
  }
  int getLowerTri(int i, int j)
  {
    return (i >= j) ? arr[i * (i + 1) / 2 + j] : 0;
  }
  int getUpperTri(int i, int j)
  {
    return (i <= j) ? arr[n * i - i * (i - 1) / 2 + (j - i)] : 0;
  }
  int getSymmetric(int i, int j)
  {
    return (i >= j) ? arr[i * (i + 1) / 2 + j] : arr[j * (j + 1) / 2 + i];
  }

  void display(int type)
  {
    cout << endl
         << "Matrix:" << endl;
    for (int i = 0; i < n; i++)
    {
      for (int j = 0; j < n; j++)
      {
        if (type == 1)
          cout << getDiagonal(i, j) << " ";
        else if (type == 2)
          cout << getLowerTri(i, j) << " ";
        else if (type == 3)
          cout << getUpperTri(i, j) << " ";
        else if (type == 4)
          cout << getSymmetric(i, j) << " ";
      }
      cout << endl;
    }
  }

  ~Matrix()
  {
    delete[] arr;
  }
};

int main()
{
  int n, choice, x;
  cout << "Enter the order of the matrix : ";
  cin >> n;
  Matrix M(n);

  cout << "\n1. Diagonal Matrix.";
  cout << "\n2. Lower Triangular Matrix.";
  cout << "\n3. Upper Triangular Matrix.";
  cout << "\n4. Symmetric Matrix.";
  cout << "\nEnter your choice : ";
  cin >> choice;

  switch (choice)
  {
  case 1:
    cout << "\nEnter the diagonal elements : ";
    for (int i = 0; i < n; i++)
    {
      cin >> x;
      M.setDiagonal(i, i, x);
    }
    M.display(1);
    break;

  case 2:
    cout << "\nEnter the elements : ";
    for (int i = 0; i < n; i++)
    {
      for (int j = 0; j <= i; j++)
      {
        cin >> x;
        M.setLowerTri(i, j, x);
      }
    }
    M.display(2);
    break;

  case 3:
    cout << "\nEnter the elements : ";
    for (int i = 0; i < n; i++)
    {
      for (int j = i; j < n; j++)
      {
        cin >> x;
        M.setUpperTri(i, j, x);
      }
    }
    M.display(3);
    break;

  case 4:
    cout << "\nEnter the elements : ";
    for (int i = 0; i < n; i++)
    {
      for (int j = 0; j <= i; j++)
      {
        cin >> x;
        M.setSymmetric(i, j, x);
      }
    }
    M.display(4);
    break;

  default:
    cout << "Invalid Choice.";
  }
  return 0;
}